Added doc for Type func
Added doc for Type func

fromkeith/gorequest,julianshen/gorequest,roth1002/gorequest,parnurzeal/gorequest,going/requests,csrgxtu/gorequest,rockneurotiko/gorequest,vicanso/gorequest,QuentinPerez/gorequest,kemadz/gorequest,jqs7/gorequest