chore: add some annotations (#1544)

ref: #1075 
because I am not a native English, maybe have a bit problem.

render/redirect.go

@@ -9,12 +9,14 @@ import (
 	"net/http"
 )
 
+// Redirect contains the http request reference and redirects status code and location.
 type Redirect struct {
 	Code     int
 	Request  *http.Request
 	Location string
 }
 
+// Render (Redirect) redirects the http request to new location and writes redirect response.
 func (r Redirect) Render(w http.ResponseWriter) error {
 	// todo(thinkerou): go1.6 not support StatusPermanentRedirect(308)
 	// when we upgrade go version we can use http.StatusPermanentRedirect
@@ -25,4 +27,5 @@ func (r Redirect) Render(w http.ResponseWriter) error {
 	return nil
 }
 
+// WriteContentType (Redirect) don't write any ContentType.
 func (r Redirect) WriteContentType(http.ResponseWriter) {}