Clarify that `is_pixel_opaque` function gets position in local coordinates

Co-authored-by: A Thousand Ships <[email protected]>

doc/classes/Sprite2D.xml

@@ -44,7 +44,7 @@
 			<return type="bool" />
 			<param index="0" name="pos" type="Vector2" />
 			<description>
-				Returns [code]true[/code], if the pixel at the given position is opaque and [code]false[/code] in other case.
+				Returns [code]true[/code], if the pixel at the given position is opaque and [code]false[/code] in other case. The position is in local coordinates.
 				[b]Note:[/b] It also returns [code]false[/code], if the sprite's texture is [code]null[/code] or if the given position is invalid.
 			</description>
 		</method>