Add support for grouping tags. From FS#7362.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14242 a1c6a512-1295-4272-9138-f99709370657
diff --git a/docs/CREDITS b/docs/CREDITS
index 84d8d9f..4dbc2df 100644
--- a/docs/CREDITS
+++ b/docs/CREDITS
@@ -311,6 +311,7 @@
 John Zhou
 Charles Voelger
 Gerritt Gonzales
+Dieter Pellkofer
 The libmad team
 The wavpack team
 The ffmpeg team