Default branch to be renamed "main"

[jody]

This is a timely notice that the name of the default branch for the MetroCS/redistricting repository will be changed from master to main on or after 17 December 2021.

• [UserStory] Change default branch from master to main #165

Although the built-in automation should appropriately re-target pull requests, update GitHub Pages, and the like, maintainers may need to manually update their local environments. In such cases, GitHub should provide information such as the following command sequence:

git branch -m master main
git fetch origin
git branch -u origin/main main
git remote set-head origin -a

[jody]

Renaming is now complete (master → main).
Repository cloning verified.
Website regeneration and publication verified.