Added documentation

Change-Id: I4cb4c8c56642337899d0865c147b54df72b2c1fa
diff --git a/roles/ceph_mon/defaults/main.yml b/roles/ceph_mon/defaults/main.yml
index d8f595b..f001f84 100644
--- a/roles/ceph_mon/defaults/main.yml
+++ b/roles/ceph_mon/defaults/main.yml
@@ -1,16 +1,25 @@
-# Copyright (c) 2022 VEXXHOST, Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License"); you may
-# not use this file except in compliance with the License. You may obtain
-# a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
-# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
-# License for the specific language governing permissions and limitations
-# under the License.
+---
+# .. vim: foldmarker=[[[,]]]:foldmethod=marker
 
+# .. Copyright (C) 2022 VEXXHOST, Inc.
+# .. SPDX-License-Identifier: Apache-2.0
+
+# Default variables
+# =================
+
+# .. contents:: Sections
+#    :local:
+
+
+# .. envvar:: ceph_mon_group [[[
+#
+# Name of Ansible group that contains all Ceph monitors
 ceph_mon_group: ceph_mons
+
+                                                                   # ]]]
+# .. envvar:: ceph_mon_cluster_network [[[
+#
+# Cluster (replication) network used by Ceph
 ceph_mon_cluster_network: "{{ ceph_mon_public_network }}"
+
+                                                                   # ]]]