HDFS-14885. UI: Fix a typo on WebUI of DataNode. Contributed by Xieming Li.

hadoop-hdfs-project/hadoop-hdfs/src/main/webapps/hdfs/dfshealth.html

@@ -420,7 +420,7 @@
   {/DecomNodes}
 </table>
 {:else}
-No nodes are decommissioning
+No nodes are decommissioning.
 {/DecomNodes}
 </small>
 </script>