doc/filters: fix typo

Signed-off-by: Dave Rice <dave@dericed.com>
Reviewed-by: Timothy Gu <timothygu99@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

doc/filters.texi

@@ -7708,7 +7708,7 @@ ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.si
 @item
 Playback video while highlighting pixels that are outside of broadcast range in red.
 @example
-ffplay example.mov -vf values="out=brng:color=red"
+ffplay example.mov -vf signalstats="out=brng:color=red"
 @end example
 @end itemize