Ho provato così:
codice:
$ cat Dockerfile
FROM php:cli

RUN apt-get update
RUN apt-get install -y libxslt-dev graphviz
RUN docker-php-ext-install xsl

docker build -t phpdoc-docker test-dir
Sending build context to Docker daemon 5.523MB
Step 1/4 : FROM php:cli
---> 0ceab3be41fb
Step 2/4 : RUN apt-get update
---> Using cache
---> 097f829be7f2
Step 3/4 : RUN apt-get install -y libxslt-dev graphviz
---> Using cache
---> e474fcd06b7a
Step 4/4 : RUN docker-php-ext-install xsl
---> Using cache
---> d151706c4e2d
Successfully built d151706c4e2d
Successfully tagged phpdoc-docker:latest

$ docker run --rm -v phpDocumentor.phar:/usr/local/my-app/phpDocumentor.phar:ro -v mio-progetto/src:/usr/local/my-app/src:ro -v mio-progetto/docs:/usr/local/my-app/docs -w /usr/local/my-app phpdoc-docker ./phpDocumentor.phar --template=responsive --directory /usr/local/my-app/src --target /usr/local/my-app/docs
phpDocumentor v3.0.0-alpha.4-6-gc5f3834c

[2019-12-12 12:32:18] app.NOTICE: Using the configuration file at the default location [] []
[2019-12-12 12:32:18] app.INFO: Collecting files .. [] []
[2019-12-12 12:32:18] app.INFO: OK [] []
[2019-12-12 12:32:18] app.INFO: Loading project from cache [] []
[2019-12-12 12:32:18] app.NOTICE: Parsing files [] []
Parsing files
[2019-12-12 12:32:18] app.INFO: Starting to parse file: Example.php [] []
[2019-12-12 12:32:18] app.NOTICE: Parsing Example.php [] []

1/1 [============================] 100%[2019-12-12 12:32:18] app.INFO: Elapsed time to parse all files: 0.01s [] []
[2019-12-12 12:32:18] app.INFO: Peak memory usage: 14M [] []
[2019-12-12 12:32:18] app.NOTICE: Storing cache .. [] []
[2019-12-12 12:32:18] app.INFO: OK [] []
[2019-12-12 12:32:18] app.INFO: Loading project from cache [] []
[2019-12-12 12:32:18] app.INFO: Applying 13 transformations [] []

Applying transformations (can take a while)
[2019-12-12 12:32:18] app.INFO: Initialize writer "phpDocumentor\Transformer\Writer\FileIo" [] []
[2019-12-12 12:32:18] app.INFO: Initialize writer "phpDocumentor\Transformer\Writer\Xml" [] []
[2019-12-12 12:32:18] app.INFO: Initialize writer "phpDocumentor\Transformer\Writer\Xsl" [] []
[2019-12-12 12:32:18] app.INFO: Initialize writer "phpDocumentor\Transformer\Writer\Graph" [] []
[2019-12-12 12:32:18] app.NOTICE: Writer FileIo using query "copy" on img [] []

1/13 [==>-------------------------] 7%[2019-12-12 12:32:18] app.NOTICE: Writer FileIo using query "copy" on css [] []

2/13 [====>-----------------------] 15%[2019-12-12 12:32:18] app.NOTICE: Writer FileIo using query "copy" on js [] []

3/13 [======>---------------------] 23%[2019-12-12 12:32:19] app.NOTICE: Writer xml on structure.xml [] []

4/13 [========>-------------------] 30%[2019-12-12 12:32:19] app.NOTICE: Writer xsl on index.html [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

5/13 [==========>-----------------] 38%[2019-12-12 12:32:19] app.NOTICE: Writer xsl using query "//namespace/@full_name" on namespaces/{$full_name} [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

6/13 [============>---------------] 46%[2019-12-12 12:32:19] app.NOTICE: Writer xsl using query "//package/@full_name" on packages/{$full_name} [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

7/13 [===============>------------] 53%[2019-12-12 12:32:19] app.NOTICE: Writer xsl using query "//class/full_name|//interface/full_name|//trait/full_name" on classes/{$full_name} [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

8/13 [=================>----------] 61%[2019-12-12 12:32:19] app.NOTICE: Writer xsl on markers.html [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

9/13 [===================>--------] 69%[2019-12-12 12:32:19] app.NOTICE: Writer xsl on errors.html [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

10/13 [=====================>------] 76%[2019-12-12 12:32:19] app.NOTICE: Writer xsl on deprecated.html [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

11/13 [=======================>----] 84%[2019-12-12 12:32:19] app.NOTICE: Writer xsl on graph_class.html [] []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []
[2019-12-12 12:32:19] php.WARNING: Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object {"exception":"[object] (ErrorException(code: 0): Warning: XSLTProcessor::transformToUri(): No stylesheet associated to this object at phar:///usr/local/my-app/phpDocumentor.phar/src/phpDocumentor/Transformer/Writer/Xsl.php:291)"} []

12/13 [=========================>--] 92%[2019-12-12 12:32:19] app.NOTICE: Writer Graph on classes.svg [] []

13/13 [============================] 100%[2019-12-12 12:32:19] app.NOTICE: Finished transformation process [] []

All done!

Ma come vedete ci sono molti errori. Perchè?