Fix API document for String object
@@ -30,8 +30,8 @@ type RString struct {
// ```
//
// **Note:**
-// Currently, manipulations are based upon Golang's Unicode manipulations.
//
+// - Currently, manipulations are based upon Golang's Unicode manipulations.
// - Currently, UTF-8 encoding is assumed based upon Golang's string manipulation, but the encoding is not actually specified(TBD).
// - `String.new` is not supported.
type StringObject struct {
