docs: add release process steps

Author: lesnitsky

Diff for: docs/release.md

@@ -0,0 +1,14 @@
+# How to cut a new release of Firebase UI
+
+1. Switch to `main` branch locally.
+2. Run `git pull origin main`.
+3. Run `git pull --tags` to make sure all tags are fetched.
+4. Create new branch with the signature "release/[year]-[month]-[day]".
+5. Run `melos version --no-git-tag-version` to automatically version packages and update Changelogs.
+6. Run `melos publish` to dry run and confirm all packages are publishable.
+7. After successful dry run, commit all changes with the signature "chore(release): prepare for release".
+8. Run `git push origin [RELEASE BRANCH NAME]` & open pull request for review on GitHub.
+9. After successful review and merge of the pull request, switch to `main` branch locally, & run `git pull origin main`.
+10. Run `melos publish --no-dry-run --git-tag-version` to now publish to Pub.dev.
+11. Run `git push --tags` to push tags to repository.
+12. Ping @kevinthecheung to get the changelog in Firebase releases.