fix golint issues in rest (#529)

rest/handler/maxbyteshandler.go

@@ -6,6 +6,7 @@ import (
 	"github.com/tal-tech/go-zero/rest/internal"
 )
 
+// MaxBytesHandler returns a middleware that limit reading of http request body.
 func MaxBytesHandler(n int64) func(http.Handler) http.Handler {
 	if n <= 0 {
 		return func(next http.Handler) http.Handler {