doc/filters: itemize channelmap examples

Signed-off-by: Paul B Mahol <onemda@gmail.com>

doc/filters.texi

@@ -2188,6 +2188,10 @@ The channel layout of the output stream.
 If no mapping is present, the filter will implicitly map input channels to
 output channels, preserving indices.
 
+@subsection Examples
+
+@itemize
+@item
 For example, assuming a 5.1+downmix input MOV file,
 @example
 ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
@@ -2195,10 +2199,12 @@ ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav
 will create an output WAV file tagged as stereo from the downmix channels of
 the input.
 
+@item
 To fix a 5.1 WAV improperly encoded in AAC's native channel order
 @example
 ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:5.1' out.wav
 @end example
+@end itemize
 
 @section channelsplit