maint: post-release administrivia

* NEWS: Add header line for next release.
diff --git a/NEWS b/NEWS
index 1f3de08..06d3b98 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,6 @@
+Noteworthy changes in release ?.?
+=================================
+
 Noteworthy changes in release 4.7
 =================================