message: add more description on the validate Promise
  the promise is very useful, therefore I would like to add documentation to help people using it :)
diff: @@ -17,7 +17,7 @@ The validator offers an API to add new fields and trigger validations.
  |Name | Return Type |Description |
  |---------|---------|---------|
  | attach(field: FieldOptions) | `Field` | attaches a new field to the validator. |
  -| validate(descriptor?: String, value?: any, options?: Object) | `Promise<boolean>` | Validates the matching fields of the provided [descriptor](#field-descriptor). |
  +| validate(descriptor?: String, value?: any, options?: Object) | `Promise<boolean>` | Validates the matching fields of the provided [descriptor](#field-descriptor). when validation is done, the Promise resolves a boolean indicating whether the selected was valid or not. |
  | pause() | `void` | Disables validation. |
  | resume() | `void` | Enables validation. |
  | detach(name: string, scope?: string) | `void` | Detaches the field that matches the name and the scope of the provided values. |
  