docs: wiki page to docs

[dacoex]

Hello,
should this page not be added to the docs itself?

https://github.com/pvlib/pvlib-python/wiki/Projects-and-publications-that-use-pvlib-python

[wholmgren]

I thought that more people would add their projects to the wiki than would submit pull requests for the docs. What's the argument for putting it in the docs?