doc/filters: itemize shuffleframes & shuffleplanes examples

Add one more shuffleframes example.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -12113,11 +12113,22 @@ frames. Number of indexes also sets maximal value that each index may have.
 
 The first frame has the index 0. The default is to keep the input unchanged.
 
+@subsection Examples
+
+@itemize
+@item
 Swap second and third frame of every three frames of the input:
 @example
 ffmpeg -i INPUT -vf "shuffleframes=0 2 1" OUTPUT
 @end example
 
+@item
+Swap 10th and 1st frame of every ten frames of the input:
+@example
+ffmpeg -i INPUT -vf "shuffleframes=9 1 2 3 4 5 6 7 8 0" OUTPUT
+@end example
+@end itemize
+
 @section shuffleplanes
 
 Reorder and/or duplicate video planes.
@@ -12142,10 +12153,15 @@ The index of the input plane to be used as the fourth output plane.
 
 The first plane has the index 0. The default is to keep the input unchanged.
 
+@subsection Examples
+
+@itemize
+@item
 Swap the second and third planes of the input:
 @example
 ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT
 @end example
+@end itemize
 
 @anchor{signalstats}
 @section signalstats