Move changelog entry to right section (#4326)

Crashes are usually documented in the stable style portion of the
changelog. This patch doesn't affect the parser (e.g. blib2to3).
Noticed the second after I merged :-)

CHANGES.md

@@ -12,6 +12,8 @@
 
 <!-- Changes that affect Black's stable style -->
 
+- Fix crash involving indented dummy functions containing newlines (#4318)
+
 ### Preview style
 
 <!-- Changes that affect Black's preview style -->
@@ -28,9 +30,6 @@
 
 <!-- Changes to the parser or to version autodetection -->
 
-- Add support to style function definitions containing newlines before function stubs
-  (#4318)
-
 ### Performance
 
 <!-- Changes that improve Black's performance. -->