Add changelog project URL

[scop]

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you added an explanation of what your changes do and why you'd like us to include them?

Code changes:

• Did you format your code with Black?
  • black getmac tests
• Are the linting checks passing?
  • tox -e check
• Do all tests pass locally?
  • tox
• Have you updated the CHANGELOG with a summary of your change?
• Did you add your name to the contributors list in the README?

Summary of changes:

Background info at
pypi/warehouse#7882 (comment)

[GhostofGoes]

While the changelog is already included on the bottom of the PyPI description I suppose it doesn't hurt to have a link to the file as well.

[scop]

Thanks! The point of the link is consistency; most projects maintain a changelog, but without these links it has to be hunted down differently for each project. Some have it in README, sometimes top, sometimes bottom, sometimes embedded, sometimes not there at all. With a project URL in metadata, it's always easily accessible in the same place.