changed grammer link

templates/grammar.html

@@ -12,6 +12,7 @@
     <a href="singlish.html">Advance Singlish</a>
     <a href="grammar.html">Advance Grammar</a>
     <a href="summarize.html">Advance Summarize</a>
+    <!-- calling navigations -->
     <!-- Add more links for other sections or pages -->
 </div>
 <script src="../static/script.js"></script>