Rename master to main?

@astro, what would you think of renaming the `master` branch to `main`? These days, most projects seem to use `main` to name their default branch, perhaps because it’s the default when creating a new project on GitHub. (Probably also on other code hosting platforms, though I haven’t checked). I don’t really have strong opinions on such things, just wondering whether it might make sense to be consistent with the general practice, since it’s a bit confusing when names are different. I’ll of course do the “work”, but wanted to ask you first.

The issue proposes renaming the repository's master branch to main; begin by checking the repository's current default-branch configuration. Done means the default branch is main and the branch rename is completed.

Written by the indexing model from the issue text.