[stable/moodle] Fix chart not being upgradable (#7860)

Signed-off-by: Javier J. Salmeron Garcia <jsalmeron@bitnami.com>

stable/moodle/Chart.yaml

@@ -1,5 +1,5 @@
 name: moodle
-version: 2.0.5
+version: 3.0.0
 appVersion: 3.5.2
 description: Moodle is a learning platform designed to provide educators, administrators
   and learners with a single robust, secure and integrated system to create personalised

stable/moodle/README.md

@@ -179,3 +179,15 @@ The [Bitnami Moodle](https://github.com/bitnami/bitnami-docker-moodle) image sto
 Persistent Volume Claims are used to keep the data across deployments. This is known to work in GCE, AWS, vpshere, and minikube.
 See the [Configuration](#configuration) section to configure the PVC or to disable persistence.
 You may want to review the [PV reclaim policy](https://kubernetes.io/docs/tasks/administer-cluster/change-pv-reclaim-policy/) and update as required. By default, it's set to delete, and when Moodle is uninstalled, data is also removed.
+
+## Upgrading
+
+### To 3.0.0
+
+Backwards compatibility is not guaranteed unless you modify the labels used on the chart's deployments.
+Use the workaround below to upgrade from versions previous to 3.0.0. The following example assumes that the release name is moodle:
+
+```console
+$ kubectl patch deployment moodle-moodle --type=json -p='[{"op": "remove", "path": "/spec/selector/matchLabels/chart"}]'
+$ kubectl delete statefulset moodle-mariadb --cascade=false
+```

stable/moodle/templates/deployment.yaml

@@ -8,6 +8,10 @@ metadata:
     release: "{{ .Release.Name }}"
     heritage: "{{ .Release.Service }}"
 spec:
+  selector:
+    matchLabels:
+      app: {{ template "moodle.fullname" . }}
+      release: "{{ .Release.Name }}"
   template:
     metadata:
       labels: