Change default base branch: master -> main

[janosh]

Since GitHub changed the name of the default branch on new repos to main on Oct 1, 2020, changesets might consider updating the default baseBranch to match:

$ yarn changeset init
$ cat .changeset/config.json
{
  "$schema": "https://unpkg.com/@changesets/config@1.6.2/schema.json",
  "changelog": "@changesets/cli/changelog",
  "commit": false,
  "linked": [],
  "access": "restricted",
- "baseBranch": "master",
+ "baseBranch": "main",
  "updateInternalDependencies": "patch",
  "ignore": []
}

[Andarist]

There are might be couple of places in the codebase where we default to master - and I think we can't change them right now, in the current major version, because that would be a breaking change. The init command, IMHO, can be changed though - because this is targeting new users.

@janosh would you like to prepare a PR with such a change?

[BryanAdamss]

Can baseBranch set multiple values?
like
baseBranch:["main","master"]

[Andarist]

I somewhat doubt it (I think that some code might depend on this being a single value and this might not be that easy to change without introducing breaking changes). What that would even mean though?