On the 'multi-wc-format' branch: add a CHANGES log entry.

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/multi-wc-format@1897944 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/CHANGES b/CHANGES
index 1bc9c05..b2b6b48 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,9 @@
 Version 1.15.0
 (?? ??? 20XX, from /branches/1.15.x)
 https://svn.apache.org/repos/asf/subversion/tags/1.15.0
+ User-visible changes:
+  - Client-side improvements and bugfixes:
+    * Support multiple working copy formats (1.8-onward, 1.15) (issue #????)
 
 Version 1.14.1
 (10 Feb 2021, from /branches/1.14.x)