Mention defvar'ed variable name in ChangeLog

Author: matsl

ChangeLog

@@ -1,8 +1,8 @@
 2025-11-07  Mats Lidell  <matsl@gnu.org>
 
 * hsys-www.el (eww--dwim-expand-url): Declare function to silence warning.
-    (www-eww-browse-url): Defvar to silence warning in Emacs 28 where it
-    is not defined. Introduced with Emacs 29.
+    (www-eww-browse-url): Defvar url-allow-non-local-files to silence
+    warning in Emacs 28 where it is not defined. Introduced with Emacs 29.
 
 2025-11-06  Mats Lidell  <matsl@gnu.org>