Update layer-heatmap.html

Author: NicolasBonduel

testapp/layer-heatmap.html

@@ -71,7 +71,7 @@
       <button ng-click="vm.changeOpacity()">Change opacity</button>
     </div>
     <ng-map zoom="13" center="37.774546, -122.433523" map-type-id="SATELLITE">
-      <heatmap-layer id="foo" data="taxiData"></heatmap>
+      <heatmap-layer id="foo" data="taxiData"></heatmap-layer>
     </ng-map>
   </div>
 </body>