Update alerta chart release notes to latest

This change updates the release notes for each update to the alerta
chart as of this patchset.

Change-Id: Ice57fba7df2e029512ff0ed9d7912fb9128876af

releasenotes/notes/alerta.yaml

@@ -1,4 +1,9 @@
 ---
 alerta:
   - 0.1.0 Initial Chart
+  - 0.1.1 Fix values reference in ingress manifests
+  - 0.1.2 Change helm-toolkit dependency version to ">= 0.1.0"
+  - 0.1.3 Alerta update to silence alert in Alertmanager
+  - 0.1.4 Add missing pod/container flags to alerta
+  - 0.1.5 Add pod/container security context template to create_db.yaml
 ...