(DOCSP-21888): Created Prometheus tutorial. (#909)

* (DOCSP-21888): Created Prometheus tutorial.

* (DOCSP-21888): Incorporated Rodrigo's feedback.

* (DOCSP-21888): Incorporated Mircea's feedback.

* (DOCSP-21888): Incorporated JW's feedback.

Author: corryroot

source/deploy.txt

@@ -23,6 +23,10 @@ Deploy a MongoDB Database Resource
 :ref:`deploy-sharded-cluster`
   Use |k8s-op-short| to deploy a sharded cluster.
 
+:ref:`deploy-prometheus`
+  Use |k8s-op-short| to deploy a MongoDB resource to use with 
+  Prometheus monitoring enabled.
+
 .. class:: hidden
 
    .. toctree::
@@ -31,3 +35,4 @@ Deploy a MongoDB Database Resource
       /tutorial/deploy-standalone
       /tutorial/deploy-replica-set
       /tutorial/deploy-sharded-cluster
+      /tutorial/deploy-prometheus

source/reference/k8s-operator-specification.txt

@@ -206,7 +206,10 @@ Prometheus Settings
 -------------------
 
 You can use Prometheus with your standalone resource, replica sets, or 
-sharded clusters. The following settings apply when you use Prometheus 
+sharded clusters. To learn more, see :ref:`deploy-prometheus`. To view 
+an example, see :ref:`mdb-resource-prometheus`.
+
+The following settings apply when you use Prometheus 
 with your MongoDB resource:
 
 .. setting:: spec.prometheus