Added a tooltip to the hamburger button that toggles the right-hand menu.

bigbluebutton-html5/app/client/main.html

@@ -37,9 +37,7 @@
       {{> makeButton id="logout" btn_class="signOutIcon navbarButton" i_class="ion-log-out" rel="tooltip"
       title="Logout"}}
     </div>
-    <button class="btn toggleMenuButton navbarButton sl-hamburger sl-ham-ra-cw sl-portrait-mobile sl-portrait-keyboard">
-      <span></span>
-    </button>
+    {{> makeButton btn_class="btn toggleMenuButton navbarButton sl-hamburger sl-ham-ra-cw sl-portrait-mobile sl-portrait-keyboard" rel="tooltip" title="Toggle Menu" span=true}}
   </nav>
 </template>