Merge pull request #23 from canonical/feature/improve-readme

improve README

README.md

@@ -3,8 +3,13 @@
 [![Publish to GHCR:dev](https://github.com/canonical/prometheus-rock/actions/workflows/rock-release-dev.yaml/badge.svg)](https://github.com/canonical/prometheus-rock/actions/workflows/rock-release-dev.yaml)
 [![Update ROCK](https://github.com/canonical/prometheus-rock/actions/workflows/rock-update.yaml/badge.svg)](https://github.com/canonical/prometheus-rock/actions/workflows/rock-update.yaml)
 
-Automation for building a ROCK for Prometheus. Every fourth hour, the automation checks whether 
-a new release has been cut in the upstream Prometheus repo, and if so, creates a pull request with 
-the new version info.
+[ROCKs](https://canonical-rockcraft.readthedocs-hosted.com/en/latest/) for [Prometheus](https://prometheus.io/).  
+This repository holds all the necessary files to build ROCKs for the upstream versions we support. The Prometheus ROCK is used by the [prometheus-k8s-operator](https://github.com/canonical/prometheus-k8s-operator) charm.
+
+The ROCKs on this repository are built with [OCI Factory](https://github.com/canonical/oci-factory/), which also takes care of periodically rebuilding the images. We usually support our ROCKs for about six months from the release date.
+
+Automation takes care of:
+* validating PRs, by simply trying to build the ROCK;
+* pulling upstream releases, creating a PR with the necessary files to be manually reviewed;
+* releasing to GHCR at [ghcr.io/canonical/prometheus:dev](https://ghcr.io/canonical/prometheus:dev), when merging to main, for development purposes.
 
-Once the PR gets merged, a new ROCK is built and published on ghcr.io/canonical/prometheus.