Rename master branch to main

[basnijholt]

This change is very easy (https://github.com/github/renaming).

Any objections @jbweston or @akhmerov?

[akhmerov]

I'm OK with that.

[jbweston]

I am fine also

[basnijholt]

Great! I have just made the change.

As GitHub will tell you.

If you have a local clone, you can update it by running the following commands.

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