Docs improvements tracker and ReadTheDocs warnings

[echedey-ls]

In the hope this issue becomes something like a tracker of small enhancements that can be done to the docs. Feel free to comment anything you spotted but were unsure if an issue was the right choice.

From my experience, these are some possible good first contributions to start learning the Sphinx environment:

• The first line description of this FAQ section can make use of a :py:mod: role to link to the iotools module.

For the veterans preferably:

• Some pages could make use of an update:
  • comparison_pvlib_matlab.rst in general. Issue Update Comparison with PVLIB MATLAB #2010
  • contributing.rst regarding the IPython/Jupyter notebooks, I recall they were deprecated from some PR I did some time ago. Maybe it just needs an update to the examples gallery. PR Remove link to outdated tutorials #2009
  • The FAQ could also have some new entries added. Just have a quick glance at the mailing list for possible ideas.
    BTW, searching for "frequently asked questions" in the readthedocs search box show reasonable results, but for "FAQ" does not. Any idea of how can this be solved?

I will add more finds as I see them.