DOCS-4584: clarify version added date

Author: Sam Kleinman

source/includes/options-mongod.yaml

@@ -1262,7 +1262,7 @@ name: sslAllowInvalidCertificates
 args: null
 directive: option
 description: |
-  .. versionadded:: 2.6
+  .. versionadded:: 2.6.4
 
   Bypasses the validation checks for SSL certificates on other servers
   in the cluster and allows the use of invalid certificates. When using