Changed a @method string so the documentation method name matches the code method name.

Author: kay-is

src/loader/Cache.js

@@ -833,7 +833,7 @@ Phaser.Cache.prototype = {
     /**
     * Get tilemap data by key.
     *
-    * @method Phaser.Cache#getTilemap
+    * @method Phaser.Cache#getTilemapData
     * @param {string} key - Asset key of the tilemap data to retrieve from the Cache.
     * @return {Object} The raw tilemap data in CSV or JSON format.
     */