Add instructions to build documentation

[dmlls]

Pull request

This PR adds a README.md in the docs directory with a short explanation on how to build the docs. This might be especially useful for people coming from non-technical backgrounds in order to be able to contribute to the documentation.

How Has This Been Tested?

The requirements have been frozen by installing the latest versions of sphinx-argparse and pdfminer.six and running pip freeze > requirements.txt.

Afterwards, I've created a virtual environment, installed the requirements and checked that the build was successful.

Checklist

• I have read CONTRIBUTING.md.
• I have added a concise human-readable description of the change to CHANGELOG.md.
• I have tested that this fix is effective or that this feature works.
• I have added docstrings to newly created methods and classes.
• I have updated the README.md and the readthedocs documentation. Or verified that this is not necessary.

[pettzilla1]

Hi are the requirements listed just all the current requirements of the package or have additional requirements been added ?

[dmlls]

Hi @pettzilla1, no additional requirements have been added.

As mentioned above, I installed sphinx-argparse and pdfminer.six, which are required to build the docs. The rest of the modules are just dependencies of those.

[pietermarsman]

Hi @dmlls,

Thanks for this setup! I've rewrote the readme in active phrases and will merge it now.