message: docs: update errorbag example
diff: @@ -8,10 +8,13 @@ import { ErrorBag } from 'vee-validate';
  const bag = new ErrorBag();
  // For example, you may want to add an error related to authentication:
  -bag.add('email', 'Wrong Credentials', 'auth');
  +bag.add({
  + field: 'auth',
  + msg: 'Wrong Credentials'
  +});
  // Display it like this:
  -bag.first('email:auth');
  +bag.first('auth');
  ```
  The single error object looks like this:
  @@ -44,4 +47,3 @@ const error = {
  | remove(field: string, scope?: string) | `void`| Removes all errors associated with a specific field, specifying a scope will remove messages only for that field and scope.|
  | removeById(id: string) | `void` | Removes a field which matches the provided id.
  | update(id: string, diff: ErrorObject) | `void` | Updates a specific field's erorr messages data, used internally to keep field errors scope up to date.|
  -
  