fix release notes links. Add diff link

[FoamyGuy]

While using the new release automation I came across a few things in need of tweaking.

This change covers three main things:

• fix the pip installation command in the release notes. It was previously incorrectly using the full shorthand library name which will not work with pip install it must have adafruit-circuitpython- preceding the library name. To solve this I changed the function to accept the shorthand name and then used that to create the pypi name and docs URL from it.
• Remove an errant "main" chunk of code that was leftover from development. Prior to my other changes this had gone unnoticed because it didn't cause any trouble.
• added the Github 'changes' link to the release notes that are posted. The link got printed into the terminal of the person running the release automation this makes it so that effectively the same link is put into the release notes.

[FoamyGuy]

The latest commit adds one additional change which is adding timeout=30 to all requests function calls. Somewhere along the line this became one of the pylint checks and none of our calls used the timeout argument so all of them failed this check in pylint.

[tekktrik]

I didn't test this, but it all makes sense to me!

[FoamyGuy]

closing in favor of #389