Added release notes for python-pillow#9066

Author: radarhere

docs/releasenotes/12.0.0.rst

@@ -119,18 +119,10 @@ Pillow 13 (2026-10-15). They have been set to ``None`` since Pillow 2.3.0.
 API changes
 ===========
 
-TODO
-^^^^
+Image.alpha_composite: LA images
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-TODO
-
-API additions
-=============
-
-TODO
-^^^^
-
-TODO
+:py:meth:`~PIL.Image.alpha_composite` can now use LA images as well as RGBA.
 
 Other changes
 =============