move Matlab references to history

[cwhanse]

• Closes Update Comparison with PVLIB MATLAB #2010
• I am familiar with the contributing guidelines
• [ ] Tests added
• [ ] Updates entries in docs/sphinx/source/reference for API changes.
• Adds description and name entries in the appropriate "what's new" file in docs/sphinx/source/whatsnew for all changes. Includes link to the GitHub Issue with :issue:`num` or this Pull Request with :pull:`num`. Includes contributor name and/or GitHub username (link with :ghuser:`user`).
• [ ] New code is fully documented. Includes numpydoc compliant docstrings, examples, and comments where necessary.
• Pull request is nearly complete and ready for detailed review.
• Maintainer: Appropriate GitHub Labels (including remote-data) and Milestone are assigned to the Pull Request and linked Issue.

Deletes "comparison with Matlab page" from user guide, and makes minor edits elsewhere in document pages.

[AdamRJensen]

Maybe also delete this reference to matlab:

pvlib-python/pvlib/irradiance.py

Line 1778 in c2ac022

uses absolute airmass. PVLib Matlab also uses the absolute airmass.

[cwhanse]

Maybe also delete this reference to matlab:

pvlib-python/pvlib/irradiance.py

Line 1778 in c2ac022

uses absolute airmass. PVLib Matlab also uses the absolute airmass.

I would leave that mention in the docstring, since we're explaining why the code deviates from the first reference. We spent a lot of time resolving these kind of discrepancies when we put the Matlab toolbox together.