diff --git a/docs/user-guide/configmap/index.md b/docs/user-guide/configmap/index.md
index 49399cde0e..ae5880c162 100644
--- a/docs/user-guide/configmap/index.md
+++ b/docs/user-guide/configmap/index.md
@@ -605,4 +605,4 @@ 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.)
 
-NOTE: The key-value optional:true is supported for Kubernetes 1.6 and above.
+**NOTE:** The key-value `optional:true` is supported for Kubernetes 1.6 and above.