doc/bsf: document noise bitstream filter

Partially addresses ticket #3198.
Signed-off-by: Lou Logan <lou@lrcd.com>
Signed-off-by: Timothy Gu <timothygu99@gmail.com>

doc/bitstream_filters.texi

@@ -121,6 +121,13 @@ ffmpeg -i frame_%d.jpg -c:v copy rotated.avi
 
 @section noise
 
+Damages the contents of packets without damaging the container. Can be
+used for fuzzing or testing error resilience/concealment.
+
+@example
+ffmpeg -i INPUT -c copy -bsf noise output.mkv
+@end example
+
 @section remove_extra
 
 @c man end BITSTREAM FILTERS