doc: update PIL reference to Pillow

bgilbert · bgilbert · commit 1f58432338ba · 2023-07-21T22:23:42.000-04:00
Signed-off-by: Benjamin Gilbert &lt;bgilbert@cs.cmu.edu&gt;
diff --git a/doc/index.rst b/doc/index.rst
@@ -286,8 +286,8 @@ Exceptions
    Subclass of :exc:`OpenSlideError`.
 
 
-Wrapping a PIL Image
-====================
+Wrapping a Pillow Image
+=======================
 
 .. class:: ImageSlide(file)
 
