Added an option to disable known_hosts autopopulation

Prod-Related: PROD-34958
Change-Id: Idb8e79f3442b730bab0ea17614f9563cf539174a
diff --git a/README.rst b/README.rst
index ed5cb0f..9e7a3b1 100644
--- a/README.rst
+++ b/README.rst
@@ -30,6 +30,15 @@
                 key: ${_param:root_private_key}
               user: ${linux:system:user:root}
 
+* The OpenSSH client known_hosts autopopulation control:
+
+  .. code-block:: yaml
+
+      openssh:
+        client:
+          enabled: true
+          known_hosts_autopopulation: false
+
 * The OpenSSH client configuration with an individual private key and known
   host: