Fix a typo in the can_set_fullscreen() function defined on the Player struct

[stanekondrej]

There is a typo in the doc comment in the can_set_fullscreen() function definition. It is a very simple fix, but I'm too lazy to fork the repo, so I'm posting it here.

Queries the player to see if it can be asked to entrer fullscreen.
See that "entrer?" Extra r.

permalink to the line

[Mange]

Thank you. I'll see when I get to it. :-)