Add Prometheus alert for API availability

Change-Id: Ie57217ac43a1477227e1e4870e47a3bf84a13ee5
diff --git a/metadata/service/support.yml b/metadata/service/support.yml
index 30f66d4..39ef63a 100644
--- a/metadata/service/support.yml
+++ b/metadata/service/support.yml
@@ -13,3 +13,5 @@
         enabled: true
       grafana:
         enabled: true
+      prometheus:
+        enabled: true