message: also mention OAuthBuilder
diff: /// Create a [`HashSet`](std::collections::HashSet) from a list of `&str` (which
  /// will be converted to String internally), to easily create scopes for
  -/// [`Token`](crate::oauth2::Token).
  +/// [`Token`](crate::oauth2::Token) or
  +/// [`OAuthBuilder`](crate::oauth2::OAuthBuilder).
  ///
  /// Example:
  ///
  