Auto-generate API documentation

[osma]

For users and especially developers getting familiar with the Annif codebase, it would help a lot to set up browsable API documentation generated using e.g. Sphinx. It could then be published on ReadTheDocs.

[osma]

This PyCon 2018 talk by Carol Willing seems like a good introduction to the subject

Note that at this stage we would still keep the non-API documentation in the GitHub wiki.

[osma]

Another tutorial that looks good https://samnicholls.net/2016/06/15/how-to-sphinx-readthedocs/

[kinow]

+1

We generate the API documentation with Sphinx, though not using readthedocs, but instead a github pages site. Then the generated API is included in the manual part of the site as a per-section doc, and as a single page. For that, we had to customize the setuptools integration a bit.

But the hard work had been done some time ago in putting a theme and structure in a conf.py settings file.