diff --git a/docs/user-guide/configmap/index.md b/docs/user-guide/configmap/index.md
index e2de3a7aec..5e074e5787 100644
--- a/docs/user-guide/configmap/index.md
+++ b/docs/user-guide/configmap/index.md
@@ -591,4 +591,4 @@ created using kubectl, or indirectly via a replication controller.  It does not
 via the Kubelet's `--manifest-url` flag, its `--config` flag, or its REST API (these are not common
 ways to create pods.)
 
-The key-value "optional:true" will be work after kubernetes 1.5.2.
+NOTE: The key-value optional:true is supported for kubernetes 1.5.3 and above.