doc/bsfs: Fix bsf options divider in documentation

The actual implementation uses ':' divider, not '/' as
documented.
Signed-off-by: Jan Sebechlebsky <sebechlebskyjan@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

doc/bitstream_filters.texi

@@ -18,7 +18,7 @@ comma-separated list of filters, whose parameters follow the filter
 name after a '='.
 
 @example
-ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT
+ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1:opt2=str2][,filter2] OUTPUT
 @end example
 
 Below is a description of the currently available bitstream filters,