Add cluster config settings to docs

doc/ref/configuration/master.rst

@@ -193,6 +193,50 @@ following the Filesystem Hierarchy Standard (FHS) might set it to
 
     pki_dir: /etc/salt/pki/master
 
+
+.. conf_master:: cluster_id
+
+``cluster_id``
+--------------
+
+.. versionadded:: 3007
+
+When defined the master will operate in cluster mode. The master will send the cluster key and id to minions instead of it's own key and id. The master will also forward it's local event bus to other master defined by ``cluster_peers``
+
+
+.. code-block:: yaml
+
+    cluster_id: master
+
+.. conf_master:: cluster_peers
+
+``cluster_peers``
+-----------------
+
+.. versionadded:: 3007
+
+When ``cluster_id`` is defined. This setting is a list of other master (hostnames or ips) that will be in the cluster.
+
+.. code-block:: yaml
+
+    cluster_peers:
+       - master2
+       - master3
+
+.. conf_master:: cluster_pki_dir
+
+``cluster_pki_dir``
+-------------------
+
+.. versionadded:: 3007
+
+When ``cluster_id`` is defined. This sets the location of where this cluster will store it's cluster publich and private key as well as any minion keys. This setting will default to the value of ``pki_dir``, but should be changed filesystem location shared between peers in the cluster.
+
+.. code-block:: yaml
+
+    cluster_pki: /my/gluster/share/pki
+
+
 .. conf_master:: extension_modules
 
 ``extension_modules``