chore: add some annotations (#1544)

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

render/yaml.go

@@ -10,12 +10,14 @@ import (
 	"gopkg.in/yaml.v2"
 )
 
+// YAML contains the given interface object.
 type YAML struct {
 	Data interface{}
 }
 
 var yamlContentType = []string{"application/x-yaml; charset=utf-8"}
 
+// Render (YAML) marshals the given interface object and writes data with custom ContentType.
 func (r YAML) Render(w http.ResponseWriter) error {
 	r.WriteContentType(w)
 
@@ -28,6 +30,7 @@ func (r YAML) Render(w http.ResponseWriter) error {
 	return nil
 }
 
+// WriteContentType (YAML) writes YAML ContentType for response.
 func (r YAML) WriteContentType(w http.ResponseWriter) {
 	writeContentType(w, yamlContentType)
 }