Added export option in Help modal

public/app/partials/help_modal.html

@@ -32,6 +32,10 @@
 				<td><span class="label label-info">CTRL+S</span></td>
 				<td>Save dashboard</td>
 			</tr>
+      <tr>
+        <td><span class="label label-info">CTRL+E</span></td>
+        <td>Export dashboard</td>
+      </tr>
 			<tr>
 				<td><span class="label label-info">CTRL+H</span></td>
 				<td>Hide row controls</td>