Update responder README

README.md

@@ -4,9 +4,36 @@ Responder provides a means to respond differently according to a request's accep
 
 [![GoDoc](https://godoc.org/github.com/qor/responder?status.svg)](https://godoc.org/github.com/qor/responder)
 
-## Documentation
+## Usage
 
-<https://doc.getqor.com/helpers/responder.html>
+### Register mime type
+
+```go
+import "github.com/qor/responder"
+
+responder.Register("text/html", "html")
+responder.Register("application/json", "json")
+responder.Register("application/xml", "xml")
+```
+
+[Responder](https://github.com/qor/responder) has the above 3 mime types registered by default. You can register more types with the `Register` function, which accepts 2 parameters:
+
+1. The mime type, like `text/html`
+2. The format of the mime type, like `html`
+
+### Respond to registered mime types
+
+```go
+func handler(writer http.ResponseWriter, request *http.Request) {
+  responder.With("html", func() {
+    writer.Write([]byte("this is a html request"))
+  }).With([]string{"json", "xml"}, func() {
+    writer.Write([]byte("this is a json or xml request"))
+  }).Respond(request)
+})
+```
+
+The first `html` in the example will be the default response type if [Responder](https://github.com/qor/responder) cannot find a corresponding mime type.
 
 ## License