Add deployment messages so you can easier find them

If you decide to apply infamous advice and move fast and break things, then you should be prepared to fall back to a working version. Luckily Firebase Hosting allows rollback quickly, but there's one problem: it's hard to determine which version you need. To solve this problem, you can mark deployments with current git tag or link to commit at GitHub:

firebase deploy \
  --message "https://github.com/username/repo/commit/$(git rev-parse HEAD)"

Then when you move too fast and finally break things, you can easily find the version you need: