Tweaked the release email text.

 - Legacy-Id: 11869

Author: levkowetz

bin/mkrelease

@@ -260,8 +260,8 @@ $changes
 The new version is available for installation through SVN checkout, with
   'svn checkout https://svn.tools.ietf.org/svn/tools/$PROJ/tags/$VER'
 
-For development, check out the new development version instead:
-  'svn checkout https://svn.tools.ietf.org/svn/tools/$PROJ/tags/dev/$DEV'
+For development, copy the new development version instead:
+  'svn copy https://svn.tools.ietf.org/svn/tools/$PROJ/tags/dev/$DEV' <YOURBRANCH>
 
 Regards,