remove obsolete RELEASE_CHECKLIST

See https://f-droid.org/docs/Release_Process/

RELEASE_CHECKLIST.md

@@ -1,23 +0,0 @@
-
-# Release Checklist
-
-This is the things that need to happen for all releases, alpha or stable:
-
-* pull translations from Weblate: ./tools/pull-trans.sh
-
-* rebase Weblate in its web interface, since we squash commits
-
-* update `versionCode` in _app/build.gradle_
-
-* make signed tag with version name
-
-* update _metadata/org.fdroid.fdroid.txt_ in _fdroiddata_
-
-## Stable releases
-
-For stable releases, there are a couple more steps to do __before__
-making the release tag:
-
-* update CHANGELOG.md
-
-* run `./tools/trim-incomplete-translations-for-release.py`