Merge pull request #5410 from radarhere/not_special

Changed wording to avoid confusion with IMAGING_TYPE_SPECIAL

Author: hugovk

docs/handbook/concepts.rst

@@ -44,7 +44,7 @@ supports the following standard modes:
     * ``I`` (32-bit signed integer pixels)
     * ``F`` (32-bit floating point pixels)
 
-Pillow also provides limited support for a few special modes, including:
+Pillow also provides limited support for a few additional modes, including:
 
     * ``LA`` (L with alpha)
     * ``PA`` (P with alpha)