Adding API docs for the tileManager property

lib/OpenLayers/Map.js

@@ -370,6 +370,14 @@ OpenLayers.Map = OpenLayers.Class({
      *     property at the time the control is added to the map. 
      */
     displayProjection: null,
+    
+    /**
+     * APIProperty: tileManager
+     * {<OpenLayers.TileManager>} If configured at construction time, the map
+     * will use the TileManager to queue image requests and to cache tile image
+     * elements.
+     */
+    tileManager: null,
 
     /**
      * APIProperty: fallThrough