message: Correct email requirement in local register
diff: @@ -242,7 +242,7 @@ Use HTTP POST method.
  | Variable | Type | Required | Comment |
  | --------------- | ------------- | -------- | -------------------- |
  -| `email` | `string` | YES | |
  +| `email` | `string` | NO | |
  | `username` | `string` | YES | can be same as email |
  | `password` | `string` | YES | |
  | `register_data` | `json object` | NO | |
  