Adding README pillar for openssh.client for .ssh/config setup

Prod-Related: PROD-35388
Change-Id: I27b8c8fed552b55dd1327621e1a48ad39b917fc0
diff --git a/README.rst b/README.rst
index 9e7a3b1..d7fb88a 100644
--- a/README.rst
+++ b/README.rst
@@ -39,6 +39,25 @@
           enabled: true
           known_hosts_autopopulation: false
 
+* The OpenSSH client .ssh/config manipulation:
+
+  .. code-block:: yaml
+
+      openssh:
+        client:
+          enabled: True
+          user:
+            root:
+              enabled: True
+              user:
+                enabled: True
+                name: root
+                home: /root
+              config:
+                git.example.com:
+                  username: git
+                  identityfile: /root/.ssh/github/id_rsa.key
+
 * The OpenSSH client configuration with an individual private key and known
   host: