trace_headers: Update documentation

It also supports AV1 and (M)JPEG.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@googlemail.com>
Signed-off-by: Mark Thompson <sw@jkqxz.net>

doc/bitstream_filters.texi

@@ -632,7 +632,8 @@ Log trace output containing all syntax elements in the coded stream
 headers (everything above the level of individual coded blocks).
 This can be useful for debugging low-level stream issues.
 
-Supports H.264, H.265, MPEG-2 and VP9.
+Supports AV1, H.264, H.265, (M)JPEG, MPEG-2 and VP9, but depending
+on the build only a subset of these may be available.
 
 @section truehd_core