Fix typo on api/state 1st example

[CSefcek]

In the example the following line is mentioning twice the same variable (with the 'x'):

text: "player's x, y: #{args.state.player.x}, #{args.state.player.x}"

I've substituted the second variable with args.state.player.y so now the whole line is:

text: "player's x, y: #{args.state.player.x}, #{args.state.player.y}"