Draft release notes: Carry forward the warning for behaviour changes

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/RelNotes-1.6.3.txt

@@ -1,6 +1,28 @@
 GIT v1.6.3 Release Notes
 ========================
 
+With the next major release, "git push" into a branch that is
+currently checked out will be refused by default.  You can choose
+what should happen upon such a push by setting the configuration
+variable receive.denyCurrentBranch in the receiving repository.
+
+To ease the transition plan, the receiving repository of such a
+push running this release will issue a big warning when the
+configuration variable is missing.  Please refer to:
+
+  http://git.or.cz/gitwiki/GitFaq#non-bare
+  http://thread.gmane.org/gmane.comp.version-control.git/107758/focus=108007
+
+for more details on the reason why this change is needed and the
+transition plan.
+
+For a similar reason, "git push $there :$killed" to delete the branch
+$killed in a remote repository $there, if $killed branch is the current
+branch pointed at by its HEAD, gets a large warning.  You can choose what
+should happen upon such a push by setting the configuration variable
+receive.denyDeleteCurrent in the receiving repository.
+
+
 Updates since v1.6.2
 --------------------