Fix #1841 Add readthedocs documentation

[fnielsen]

A pull requests #1557 has added a files for Sphinx documentation
generation. The commit takes some of the changes from the PR as
well as add a configuration for readthedocs. Some changes was made
to the files from the PR: Style and which files to include in the
documentation.

Fixes #1841

Description

Add readthedocs documentation

Caveats

Please list anything which has been left out of this PR or which should be considered before this PR is accepted
Check any of the following which apply:

• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
  • I have made corresponding changes to the documentation
• This change requires new dependencies (please list)

If you make changes to the Python code

• My code passes the tox check, I can receive warnings about tests, documentation or both

Testing

readthedocs have generated code based on the branch at
https://scholia.readthedocs.io/en/feat-readthedocs-1841/

Checklist

• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have not used code from external sources without attribution
• I have considered accessibility in my implementation
• There are no remaining debug statements (print, console.log, ...)

There is a minor warning about scholia.googlescholar:10

Code has been used from the pull request #1557 of @DanielFLopez

[fnielsen]

Now running at https://scholia.readthedocs.io/en/latest/

[Daniel-Mietchen]

Adding a pointer to

• Scholia hackathon on 14 and 16 February 2022 #1807

which serves to keep an overview of things we worked on during the hackathon.