[MPlayer-translations] Polish help_mp-pl.h R 20162

[Misiek]

> I'll try to review it tomorrow and probably commit. Anyway thanks, we're
> a bit short on manpower/time now. And help was indeed waaaay outdated
> (As most other doc's unfortunatelly).
> Torinthiel

Cool:) I'll try to work with the rest of the doc's in the nearest(hope so) 
future:) and probably tune up this help a little bit:)
Miskieusz