Ensure sphinx correctly parses docstrings

[kristiankyvik]

This addresses task 1 of this issue: #990

Here are the main changes:

• The api_reference.rst is now up-to-date after running the create_api_rst.py locally and committing the generated files. Not sure it makes sense to commit all these files or if we simply want to generate them when we build the project
• Ensure that we run the create_api_rst.py script in the pre_build step. I think this makes sense, but please let me know if you thing differently. I took inspiration from how the langchain project seems to have solved this

Update 1 - Did the two following changes:

• Bumped sphinx to 5.0.0, after removing non-maintained package sphinx_panels that required an older version of sphinx
• Mocked two packages that are installed as experimental, since these where causing an error when building the docs, since the packages were expected to be installed.

Update 2 - Did the following change:

• Ensures the auto-generated docs are not commited to version control

[kristiankyvik]

Please note that I removed this package because I wanted to update sphinx to 5.0.0 since:

• We were seeing this error in the docs build pipeline (see link).
• This package, which was not being uses anywhere, is not maintained anymore (link) and impeding us to update to this more recent version of sphinx.

[kristiankyvik]

After updating sphinx to 5.0.0, when building the docs, I was running into a different error:

Handler <function process_automodsumm_generation at 0x7fedb8d30430> for event 'builder-inited' threw an exception (exception: No module named 'gpt_engineer.tools.experimental.document_chunker')
make: *** [html] Error 2

I followed the advice here and ensure that the two files were mocked when building the docs. This fixed the issue.

[TheoMcCabe]

looks good thank you