doc: fix CachedResponseHandler ResponseCacher documentation (#3476)
doc: fix CachedResponseHandler ResponseCacher documentation (#3476)

This commit changes the notion of Follow by the notion of Cache. It
tries to follow the convention used in Redirector from
RedirectHandler.swift.
Alamofire/Alamofire,yimajo/Alamofire,yimajo/Alamofire,Alamofire/Alamofire