Added note to TileMap.get_used_cells_by_id()

[tylerecouture]

Added: Note: The tile id is referred to as the tile index in other methods.
godotengine/godot-proposals#814

[akien-mga]

See the comment in the file's header:

.. Generated automatically by doc/tools/makerst.py in Godot's source tree.
.. DO NOT EDIT THIS FILE, but the TileMap.xml source instead.
.. The source is found in doc/classes or modules/<name>/doc_classes.

There's already a PR on the engine repository to address that proposal: godotengine/godot#38635.

[tylerecouture]

That renames the method for a future version. I'm just trying to clarify the docs for the current version.

[akien-mga]

That makes sense indeed for 3.2. This should be changed in the source file here: https://github.com/godotengine/godot/blob/master/doc/classes/TileMap.xml
Otherwise changes made here would be lost next time the class reference is generated.

[Calinou]

For reference, this was superseded by godotengine/godot#38686.