add badges (#286)

Make CI/CD and publishing status visible for management on https://releases.juju.is/?team=Data+Platform

Docs sync will be added as a separate PR. Please ignore the broken badge for now

Author: delgod

README.md

@@ -1,4 +1,8 @@
 # Charmed PostgreSQL VM Operator
+[![CharmHub Badge](https://charmhub.io/postgresql/badge.svg)](https://charmhub.io/postgresql)
+[![Release](https://github.com/canonical/postgresql-operator/actions/workflows/release.yaml/badge.svg)](https://github.com/canonical/postgresql-operator/actions/workflows/release.yaml)
+[![Tests](https://github.com/canonical/postgresql-operator/actions/workflows/ci.yaml/badge.svg?branch=main)](https://github.com/canonical/postgresql-operator/actions/workflows/ci.yaml?query=branch%3Amain)
+[![Docs](https://github.com/canonical/postgresql-operator/actions/workflows/sync_docs.yaml/badge.svg)](https://github.com/canonical/postgresql-operator/actions/workflows/sync_docs.yaml)
 
 ## Description