adjust notifyComment to be simplier

src/client/js/components/Admin/UserManagement.jsx

@@ -100,7 +100,8 @@ class UserManagement extends React.Component {
       </div>
     );
 
-    const notifyComment = (adminUsersContainer.state.notifyComment && <span className="text-warning">{ adminUsersContainer.state.notifyComment }</span>);
+    const notifyComment = adminUsersContainer.state.isNotifyCommentShow === true
+      ? <span className="text-warning">You should check at least one checkbox.</span> : null;
 
     const clearButton = (
       adminUsersContainer.state.searchText.length > 0