docs: added migration steps

Author: phbelitz

Makefile

@@ -28,7 +28,7 @@ uninstall:
 	kubectl delete ns $(NAMESPACE)
 
 upgrade:
-	helm upgrade connaisseur helm  -n $(NAMESPACE) --wait
+	helm upgrade connaisseur helm -n $(NAMESPACE) --wait
 
 annihilate:
 	kubectl delete all,mutatingwebhookconfigurations,clusterroles,clusterrolebindings,configmaps,secrets,serviceaccounts,crds -lapp.kubernetes.io/instance=connaisseur -n $(NAMESPACE)

docs/migrating_to_version_3.md

@@ -5,6 +5,14 @@ Connaisseur version 3.0 is out and brings along many new features, but also brea
 For those breaking changes, we've set up a [script](https://github.com/sse-secure-systems/connaisseur/blob/master/scripts/upgrade_to_version_3.py) that migrates your existing Connaisseur configuration.
 Read on for the list of most interesting changes.
 
+## How to migrate
+
+0. Read the [Major changes](#major-changes) and [API changes](#api-changes) sections to get an overview of what's new
+1. Run `python3 scripts/upgrade_to_version_3.py`
+2. Check the diff of your `helm/values.yaml` and make sure everything is as expected
+3. Run `make upgrade` or alternatively `helm upgrade connaisseur helm -n <your-namespace> --wait`
+4. Enjoy the new version :tada: :crossed_fingers:
+
 ## Major changes
 
 - NEW: Support for Cosign 2.0