doc: extend "See Also" chapters in component manuals

In particular, make "See Also" chapter rendered in HTML output.

doc/ffmpeg-bitstream-filters.texi

@@ -22,17 +22,24 @@ bitstream level modifications without performing decoding.
 
 @include bitstream_filters.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavcodec.html,libavcodec}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavcodec(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-bitstream-filters
 @settitle FFmpeg bitstream filters
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavcodec(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-codecs.texi

@@ -1105,17 +1105,24 @@ Set sample format audio decoders should prefer. Default value is
 @include decoders.texi
 @include encoders.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavcodec.html,libavcodec}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavcodec(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-codecs
 @settitle FFmpeg codecs
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavcodec(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-devices.texi

@@ -39,17 +39,24 @@ for programmatic use.
 @include indevs.texi
 @include outdevs.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavdevice.html,libavdevice}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavdevice(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-devices
 @settitle FFmpeg devices
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavformat(3), libavdevice(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-filters.texi

@@ -19,17 +19,24 @@ libavfilter library.
 
 @include filters.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavfilter.html,libavfilter}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavfilter(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-filters
 @settitle FFmpeg filters
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavfilter(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-formats.texi

@@ -144,17 +144,24 @@ of -1 enables when required by target format.
 @include demuxers.texi
 @include muxers.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavformat.html,libavformat}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavformat(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-formats
 @settitle FFmpeg formats
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavformat(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-protocols.texi

@@ -19,17 +19,24 @@ libavformat library.
 
 @include protocols.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavformat.html,libavformat}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavformat(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-protocols
 @settitle FFmpeg protocols
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavformat(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-resampler.texi

@@ -176,17 +176,24 @@ and 16, default value is 9.
 
 @c man end RESAMPLER OPTIONS
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libswresample.html}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libswresample(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-resampler
 @settitle FFmpeg Resampler
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libswresample(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-scaler.texi

@@ -118,17 +118,24 @@ are floating point number values.
 
 @c man end SCALER OPTIONS
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libswscale.html,libswscale}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libswscale(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-scaler
 @settitle FFmpeg video scaling and pixel format converter
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libswscale(3)
-@c man end
-
 @end ignore
 
 @bye

doc/ffmpeg-utils.texi

@@ -20,17 +20,24 @@ by the libavutil library.
 @include syntax.texi
 @include eval.texi
 
+@chapter See Also
+
+@ifhtml
+@url{ffmpeg.html,ffmpeg}, @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
+@url{libavutil.html,libavutil}
+@end ifhtml
+
+@ifnothtml
+ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavutil(3)
+@end ifnothtml
+
 @include authors.texi
 
 @ignore
 
 @setfilename ffmpeg-utils
 @settitle FFmpeg utilities
 
-@c man begin SEEALSO
-ffmpeg(1), ffplay(1), ffprobe(1), ffserver(1), libavutil(3)
-@c man end
-
 @end ignore
 
 @bye