doc/muxers: add "Options", "Examples", "Syntax", etc. subsections

More consistent with codec docs. Also some minor reorganization of sentences
to fit the new document hierarchy.
Signed-off-by: Timothy Gu <timothygu99@gmail.com>

doc/muxers.texi

@@ -23,6 +23,8 @@ A description of some of the currently available muxers follows.
 
 Audio Interchange File Format muxer.
 
+@subsection Options
+
 It accepts the following options:
 
 @table @option
@@ -49,6 +51,10 @@ The output of the muxer consists of a single line of the form:
 CRC=0x@var{CRC}, where @var{CRC} is a hexadecimal number 0-padded to
 8 digits containing the CRC for all the decoded input frames.
 
+See also the @ref{framecrc} muxer.
+
+@subsection Examples
+
 For example to compute the CRC of the input, and store it in the file
 @file{out.crc}:
 @example
@@ -68,8 +74,6 @@ and the input video converted to MPEG-2 video, use the command:
 ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -
 @end example
 
-See also the @ref{framecrc} muxer.
-
 @anchor{framecrc}
 @section framecrc
 
@@ -89,6 +93,8 @@ packet of the form:
 @var{CRC} is a hexadecimal number 0-padded to 8 digits containing the
 CRC of the packet.
 
+@subsection Examples
+
 For example to compute the CRC of the audio and video frames in
 @file{INPUT}, converted to raw audio and video packets, and store it
 in the file @file{out.crc}:
@@ -132,6 +138,8 @@ packet of the form:
 @var{MD5} is a hexadecimal number representing the computed MD5 hash
 for the packet.
 
+@subsection Examples
+
 For example to compute the MD5 of the audio and video frames in
 @file{INPUT}, converted to raw audio and video packets, and store it
 in the file @file{out.md5}:
@@ -200,6 +208,8 @@ See also the @ref{segment} muxer, which provides a more generic and
 flexible implementation of a segmenter, and can be used to perform HLS
 segmentation.
 
+@subsection Options
+
 This muxer supports the following options:
 
 @table @option
@@ -292,6 +302,8 @@ The pattern "img%%-%d.jpg" will specify a sequence of filenames of the
 form @file{img%-1.jpg}, @file{img%-2.jpg}, ..., @file{img%-10.jpg},
 etc.
 
+@subsection Examples
+
 The following example shows how to use @command{ffmpeg} for creating a
 sequence of files @file{img-001.jpeg}, @file{img-002.jpeg}, ...,
 taking one image every second from the input video:
@@ -354,6 +366,8 @@ Matroska container muxer.
 
 This muxer implements the matroska and webm container specs.
 
+@subsection Metadata
+
 The recognized metadata settings in this muxer are:
 
 @table @option
@@ -411,6 +425,8 @@ For example a 3D WebM clip can be created using the following command line:
 ffmpeg -i sample_left_right_clip.mpg -an -c:v libvpx -metadata stereo_mode=left_right -y stereo_clip.webm
 @end example
 
+@subsection Options
+
 This muxer supports the following options:
 
 @table @option
@@ -475,6 +491,8 @@ very long files (since writing normal MOV/MP4 files stores info about
 every single packet in memory until the file is closed). The downside
 is that it is less compatible with other applications.
 
+@subsection Options
+
 Fragmentation is enabled by setting one of the AVOptions that define
 how to cut the file into fragments:
 
@@ -531,6 +549,8 @@ as fragmented output, thus it is not enabled by default.
 Add RTP hinting tracks to the output file.
 @end table
 
+@subsection Example
+
 Smooth Streaming content can be pushed in real time to a publishing
 point on IIS with this muxer. Example:
 @example
@@ -587,6 +607,13 @@ MPEG transport stream muxer.
 
 This muxer implements ISO 13818-1 and part of ETSI EN 300 468.
 
+The recognized metadata settings in mpegts muxer are @code{service_provider}
+and @code{service_name}. If they are not set the default for
+@code{service_provider} is "FFmpeg" and the default for
+@code{service_name} is "Service01".
+
+@subsection Options
+
 The muxer options are:
 
 @table @option
@@ -639,10 +666,7 @@ Reemit PAT/PMT before writing the next packet.
 Use LATM packetization for AAC.
 @end table
 
-The recognized metadata settings in mpegts muxer are @code{service_provider}
-and @code{service_name}. If they are not set the default for
-@code{service_provider} is "FFmpeg" and the default for
-@code{service_name} is "Service01".
+@subsection Example
 
 @example
 ffmpeg -i file.mpg -c copy \
@@ -727,6 +751,8 @@ files.
 See also the @ref{hls} muxer, which provides a more specific
 implementation for HLS segmentation.
 
+@subsection Options
+
 The segment muxer supports the following options:
 
 @table @option
@@ -970,7 +996,8 @@ specified by a stream specifier. If not specified, this defaults to
 all the input streams.
 @end table
 
-Some examples follow.
+@subsection Examples
+
 @itemize
 @item
 Encode something and both archive it in a WebM file and stream it