Add title attribute to control buttons

Author: Yukaii

index.html

@@ -54,12 +54,12 @@ <h4 class="modal-title">Open HackMD from url</h4>
     <navbar>
       <div id="navbar-container">
         <div class="control-buttons">
-          <div class="pin-window"><i class="fa fa-map-pin" aria-hidden="true"></i></div>
-          <div class="home">HOME</div>
-          <div class="refresh">REFRESH</div>
-          <div class="navigate-back" style="margin: 0 1em;">&#x3C;</div>
-          <div class="navigate-foward">&#x3E;</div>
-          <div class="more-menu">...</div>
+          <div class="pin-window"><i class="fa fa-map-pin" aria-hidden="true" title="Pin window always on top"></i></div>
+          <div class="home" title="Go to Home">HOME</div>
+          <div class="refresh" title="Refresh">REFRESH</div>
+          <div class="navigate-back" style="margin: 0 1em;" title="Go back">&#x3C;</div>
+          <div class="navigate-foward" title="Go forward">&#x3E;</div>
+          <div class="more-menu" title="Open menu">...</div>
         </div>
         <div class="control-buttons">
           <div class="title"></div>