Fix docs description for all argument

src/tilemap/Tilemap.js

@@ -1417,8 +1417,9 @@ Phaser.Tilemap.prototype = {
     },
 
     /**
-     * Searches the entire map layer for the first tile matching the given index, then returns that Phaser.Tile object.
-     * If no match is found it returns null.
+     * Searches the entire map layer for the first tile or all tiles matching the given index.
+     * When `all` is false (the default), it returns a Phaser.Tile object or null.
+     * When `all` is true, it returns an array Phaser.Tile objects, or none (an empty array).
      * The search starts from the top-left tile and continues horizontally until it hits the end of the row, then it drops down to the next column.
      * If the reverse boolean is true, it scans starting from the bottom-right corner traveling up to the top-left.
      *