Add information on monitoring

Add/Update Monitoring section to explain monitoring availabilities for
each recipe.

Bug: Issue 13059
Change-Id: Ifac92555f743e021c0ed8f36107fd38d66fc28ce
diff --git a/dual-master/README.md b/dual-master/README.md
index 6cc88ea..57282cd 100644
--- a/dual-master/README.md
+++ b/dual-master/README.md
@@ -54,6 +54,12 @@
 * All the logs are forwarded to AWS CloudWatch in the LogGroup with the cluster
   stack name
 
+### Monitoring
+
+* Standard CloudWatch monitoring metrics for each component
+* Prometheus and Grafana stack is currently not available for dual-master, but a change is in progress to allow this
+ (see [Issue 12979](https://bugs.chromium.org/p/gerrit/issues/detail?id=12979))
+
 ## How to run it
 
 ### Setup
diff --git a/master-slave/README.md b/master-slave/README.md
index 2de0793..41b4170 100644
--- a/master-slave/README.md
+++ b/master-slave/README.md
@@ -145,10 +145,10 @@
 * HTTP `9080`
 * SSH `39418`
 
-### External Services
+### Monitoring
 
-If you need to setup some external services (maybe for testing purposes, such as SMTP or LDAP),
-you can follow the instructions [here](../README.md#external-services)
+* Standard CloudWatch monitoring metrics for each component
+* Optionally Prometheus and Grafana stack (see [here](../monitoring/README.md))
 
 ## Monitoring
 
diff --git a/single-master/README.md b/single-master/README.md
index 43f6d4a..4e49d79 100644
--- a/single-master/README.md
+++ b/single-master/README.md
@@ -45,6 +45,9 @@
 ### Monitoring
 
 * Standard CloudWatch monitoring metrics for each component
+* Prometheus and Grafana stack is not available for this recipe yet. However the work has been done for
+the dual-master recipe and it could be easily adapted (you can find the relevant issue
+[here](https://bugs.chromium.org/p/gerrit/issues/detail?id=13092)).
 
 ## How to run it