Class reference: Improve TileMap get_cell_atlas_coords documentation

[BlueberryGecko]

Improve documentation for the get_cell_atlas_coords in TileMaps to include the returned value if cell is empty (does not exist).

References:

• godot/scene/2d/tile_map.cpp

  Line 400 in 13ba673

  Vector2i TileMap::get_cell_atlas_coords(int p_layer, const Vector2i &p_coords, bool p_use_proxies) const {

• godot/scene/resources/2d/tile_set.cpp

  Line 3372 in 13ba673

  const Vector2i TileSetSource::INVALID_ATLAS_COORDS = Vector2i(-1, -1);

[Mickeon]

All of these descriptions do annoy me but this is an nice improvement.

One nitpick being that the commit's name could have been more specific, but that's okay.

[akien-mga]

Thanks! And congrats for your first merged Godot contribution 🎉

[BlueberryGecko]

Thank you all, and thanks for merging!

@Mickeon do you have a concrete suggestion on how to formulate it better? Maybe something like

Class reference: Describe return value of TileMap::get_cell_atlas_coords for empty cells

? I was originally afraid my commit message would get too long, but that's about the same length, haha.

Mainly asking because I'm now starting to seriously use Godot and will likely contribute more in the future.

[Mickeon]

Hey, it's all good, No worries. Yeah, that would've been a better title. Thank you for your contribution nonetheless, they're the small things that count.