manpage: restore -lavfdopts doc accidentally removed in d76ad5f2

For some reason the -lavfdopts option was documented under MEncoder
options (despite not being MEncoder-specific), and was removed
together with MEncoder documentation in commit d76ad5f227. Restore the
documentation and convert it from its own section to normal option
documentation form. Also fix the example to actually work with current
lavf.

DOCS/man/en/mplayer.1

@@ -1499,6 +1499,43 @@ Skip the proxy for IPv6 addresses.
 It will still be used for IPv4 connections.
 .
 .TP
+.B \-lavfdopts <option1:option2:...>
+Specify parameters for libavformat demuxers (\-demuxer lavf).
+Separate multiple options with a colon.
+.sp
+.RS
+Available suboptions are:
+.RE
+.RSs
+.IPs analyzeduration=<value>
+Maximum length in seconds to analyze the stream properties.
+.IPs format=<value>
+Force a specific libavformat demuxer.
+.IPs o=<key>=<value>[,<key>=<value>[,...]]
+Pass AVOptions to libavformat demuxer.
+Note, a patch to make the o= unneeded and pass all unknown options through
+the AVOption system is welcome.
+A full list of AVOptions can be found in the FFmpeg manual.
+Note that some options may conflict with MPlayer options.
+.sp 1
+.RS
+.I EXAMPLE:
+.RE
+.RSs
+.PD 0
+.IPs o=fflags=+ignidx
+.PD 1
+.RE
+.IPs probesize=<value>
+Maximum amount of data to probe during the detection phase.
+In the case of MPEG-TS this value identifies the maximum number
+of TS packets to scan.
+.IPs cryptokey=<hexstring>
+Encryption key the demuxer should use.
+This is the raw binary data of the key converted to a hexadecimal string.
+.RE
+.
+.TP
 .B \-loadidx <index file>
 The file from which to read the video index data saved by \-saveidx.
 This index will be used for seeking, overriding any index data