[MPlayer-DOCS] add some more profile info to manual

[compn]

i'd add it, but i have no clue about manpage syntax.
something like this:

Available profiles:
.IPs "protocol."
protocol (vcd dvd dvdnav file rtsp ffmpeg http etc)
.IPs "vo."
video output (use \-vo help for a list)
.IPs "ao."
audio output (use \-ao help for a list)
.IPs "extension."
filename extension (avi mpg rm flv etc)

and then some text needs to be added about these four profile prefixes
will be default for those specified options. and you can call named
profiles using -profile namedprofile.

its quite confusing.

-compn