[docs] Note StrictSlash re-direct behaviour #308 (#321)
[docs] Note StrictSlash re-direct behaviour #308 (#321)

* [docs] Note StrictSlash re-direct behaviour #308

* StrictSlash enabled routes return a 301 to the client
* As per the HTTP standards, non-idempotent methods, such as POST or PUT, will be followed with a GET by the client
* Users should use middleware if they wish to change this behaviour to return a HTTP 308.

* Update description of StrictSlash

gorilla/mux,kiip/mux,Gorilla/mux