diff --git a/Documentation/ceph-cluster-crd.md b/Documentation/ceph-cluster-crd.md
index c5b1675ba..7b47103da 100755
--- a/Documentation/ceph-cluster-crd.md
+++ b/Documentation/ceph-cluster-crd.md
@@ -112,6 +112,12 @@ If this value is empty, each pod will get an ephemeral directory to store their
   * `urlPrefix`: Allows to serve the dashboard under a subpath (useful when you are accessing the dashboard via a reverse proxy)
   * `port`: Allows to change the default port where the dashboard is served
   * `ssl`: Whether to serve the dashboard via SSL, ignored on Ceph versions older than `13.2.2`
+* `monitoring`: Settings for monitoring Ceph using Prometheus. To enable monitoring on your cluster see the [monitoring guide](Documentation/ceph-monitoring.md#prometheus-alerts).
+  * `enabled`: Whether to enable prometheus based monitoring for this cluster
+  * `rulesNamespace`: Namespace to deploy prometheusRule. If empty, namespace of the cluster will be used.
+      Recommended:
+    * If you have a single Rook Ceph cluster, set the `rulesNamespace` to the same namespace as the cluster or keep it empty.
+    * If you have multiple Rook Ceph clusters in the same Kubernetes cluster, choose the same namespace to set `rulesNamespace` for all the clusters (ideally, namespace with prometheus deployed). Otherwise, you will get duplicate alerts with duplicate alert definitions.
 * `network`: The network settings for the cluster
   * `hostNetwork`: uses network of the hosts instead of using the SDN below the containers.
 * `mon`: contains mon related options [mon settings](#mon-settings)