add myself as maintainer of ISS (with Jai's blessing)

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@16691 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

MAINTAINERS

@@ -249,6 +249,7 @@ Muxers/Demuxers:
   iff.c                                 Jaikrishnan Menon
   ipmovie.c                             Mike Melanson
   img2.c                                Michael Niedermayer
+  iss.c                                 Stefan Gehrer
   libnut.c                              Oded Shimon
   lmlm4.c                               Ivo van Poorten
   matroska.c                            Aurelien Jacobs