NEWS: added section on #4133

Signed-off-by: Balazs Scheidler <bazsi77@gmail.com>

NEWS.md

@@ -401,7 +401,10 @@ The framework consists of these changes:
     wrapped by a logging.LogHandler class so that normal Python APIs for logging
     can now be used.
 
-
+  * `db-parser()` and `grouping-by()`: added a `prefix()` option to both
+    `db-parser()` and `grouping-by()` that allows specifying an extra prefix
+    to be prepended to all name-value pairs that get extracted from messages
+    using patterns or <value> tags.
 
 ## Bugfixes