Update get_extra_radiation references

[RDaxini]

• Closes get_extra_radiation references could use an update #2333
• 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.

[RDaxini]

Ready for an initial review.
I suggested some text so that the Duffie/Beckman and Reno et al references could be linked. Other references were linked to their respective model. I removed the Partridge reference, will reinstate if someone can indicate for what it was a reference.

A notes section with some more explanation/theory might be worth considering in future.

[AdamRJensen]

DOI: https://doi.org/10.2172/15003974

Title has changed to include "revised"

[RDaxini]

Thanks. I added revised before the year, since the official title in the quotation marks still appears to be the same title. Let me know whether you think this is correct

[kandersolar]

Thanks @RDaxini!