Add a max function

[mis101bird]

Hi,
Thanks for the awesome open source contribution tutorial. This is my first time to contribute the code.
I would like to add max function to get the maximum value of an array, and the implementation is showed below.

function __getMax(max, value) {
    if(value > max){
    	max=num;
    }
    return max;
}

function max(array){
    array.reduce(__getMax);
}

I hope I could contribute this issue :)

[kentcdodds]

Sounds perfect! I'm looking forward to seeing your PR @mis101bird! 👏