Better clarify initialization of scene tiles

doc/classes/TileMapLayer.xml

@@ -5,7 +5,7 @@
 	</brief_description>
 	<description>
 		Node for 2D tile-based maps. A [TileMapLayer] uses a [TileSet] which contain a list of tiles which are used to create grid-based maps. Unlike the [TileMap] node, which is deprecated, [TileMapLayer] has only one layer of tiles. You can use several [TileMapLayer] to achieve the same result as a [TileMap] node.
-		For performance reasons, all TileMap updates are batched at the end of a frame. Notably, this means that scene tiles from a [TileSetScenesCollectionSource] may be initialized after their parent. This is only queued when inside the scene tree.
+		For performance reasons, all TileMap updates are batched at the end of a frame. Notably, this means that scene tiles from a [TileSetScenesCollectionSource] are initialized after their parent. This is only queued when inside the scene tree.
 		To force an update earlier on, call [method update_internals].
 		[b]Note:[/b] For performance and compatibility reasons, the coordinates serialized by [TileMapLayer] are limited to 16-bit signed integers, i.e. the range for X and Y coordinates is from [code]-32768[/code] to [code]32767[/code]. When saving tile data, tiles outside this range are wrapped.
 	</description>

doc/classes/TileSetScenesCollectionSource.xml

@@ -5,7 +5,7 @@
 	</brief_description>
 	<description>
 		When placed on a [TileMapLayer], tiles from [TileSetScenesCollectionSource] will automatically instantiate an associated scene at the cell's position in the TileMapLayer.
-		Scenes are instantiated as children of the [TileMapLayer] when it enters the tree. If you add/remove a scene tile in the [TileMapLayer] that is already inside the tree, the [TileMapLayer] will automatically instantiate/free the scene accordingly.
+		Scenes are instantiated as children of the [TileMapLayer] after it enters the tree, at the end of the frame (their creation is deferred). If you add/remove a scene tile in the [TileMapLayer] that is already inside the tree, the [TileMapLayer] will automatically instantiate/free the scene accordingly.
 		[b]Note:[/b] Scene tiles all occupy one tile slot and instead use alternate tile ID to identify scene index. [method TileSetSource.get_tiles_count] will always return [code]1[/code]. Use [method get_scene_tiles_count] to get a number of scenes in a [TileSetScenesCollectionSource].
 		Use this code if you want to find the scene path at a given tile in [TileMapLayer]:
 		[codeblocks]