Added and corrected comments

icon.go

@@ -10,10 +10,13 @@ type Icon struct {
 	URI IRI `xml:"uri"`
 }
 
+// NewIcon creates a new Icon. It returns a *Icon.
 func NewIcon(uri string) *Icon {
 	return &Icon{URI: IRI(uri)}
 }
 
+// Check checks the Icon for incompatibilities with RFC4287. It returns an
+// error.
 func (i *Icon) Check() error {
 	if i.URI == "" {
 		return errors.New("uri element of icon empty")