update readme

README.md

@@ -7,10 +7,21 @@
 [Rocks](https://canonical-rockcraft.readthedocs-hosted.com/en/latest/) for [Grafana](https://grafana.com/).  
 This repository holds all the necessary files to build rocks for the upstream versions we support. The Grafana rock is used by the [grafana-k8s-operator](https://github.com/canonical/grafana-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.
+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. New versions of the rock are tested using `kgoss`, which is part of [`goss`](https://github.com/goss-org/goss).
+
+**How do I interact with this repo?** This repo uses [`just`](https://github.com/casey/just) to easily run some commands:
+```
+∮ just
+Available recipes:
+    clean version               # `rockcraft clean` for a specific version
+    pack version                # Pack a rock of a specific version
+    run version=latest_version  # Run a rock and open a shell into it with `kgoss`
+    test version=latest_version # Test the rock with `kgoss`
+```
 
 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;
+* on PRs, validate the added (or modified) rocks by running `kgoss`;
 * releasing to GHCR at [ghcr.io/canonical/grafana:dev](https://ghcr.io/canonical/grafana:dev), when merging to main, for development purposes.