Rename main branch :)

[yairchu]

With the transition from master being the default branch to main, I'm find myself often in the USB type-A situation. I do either git checkout main or master by guessing which is the default branch name and always being wrong in the first few attempts.

I am trying to get over it by completing the transition so almost all repos will be main, just like the world is slowly replacing USB type-A.

(and it appears that I don't have permissions to rename the branch from GitHub's UI)