message: add doc for user_playlist_create
diff: @@ -218,7 +218,8 @@ pub trait OAuthClient: BaseClient {
  /// - name - the name of the playlist
  /// - public - is the created playlist public
  /// - description - the description of the playlist
  - /// - collaborative - if the playlist will be collaborative
  + /// - collaborative - if the playlist will be collaborative. Note:
  + /// to create a collaborative playlist you must also set public to false
  ///
  /// [Reference](https://developer.spotify.com/documentation/web-api/reference/#/operations/create-playlist)
  async fn user_playlist_create(
  