Fix docs for layer.Vector.renderOrder

[probins]

':number' doesn't make much sense to me in this context, so I'm assuming it's an error.

[fredj]

function(ol.Feature, ol.Feature):number is correct; the function is passed to goog.array.sort(arr, opt_compareFn)

[probins]

so ':number' means the function returns a number.

Ok, so the problem is this is not being correctly interpreted/parsed by jsdoc. I'll close this, and replace with #2253