[MPlayer-DOCS] little inconsistency in en/mplayer.1

[Jiri Heryan]

At line 2863:
 .IPs outdir=<dirname>
 Specify the directory to save the JPEG files to.
 If not specified, all JPEG files are written to the current directory.

should be:

 .IPs outdir=<dirname>
 Specify the directory to save the JPEG files to (default: ./).

to match following PNM section.

Jiri