input/tidal: remove defunct unmaintained plugin

This plugin has been defunct for several years.  Tidal has not ever
replied to any of my emails, so they're apparently not interested in
MPD support.

doc/plugins.rst

@@ -295,37 +295,6 @@ in the form ``qobuz://track/ID``, e.g.:
    * - **format_id N**
      - The `Qobuz format identifier <https://github.com/Qobuz/api-documentation/blob/master/endpoints/track/getFileUrl.md#parameters>`_, i.e. a number which chooses the format and quality to be requested from Qobuz. The default is "5" (320 kbit/s MP3).
 
-tidal
------
-
-Play songs from the commercial streaming service `Tidal
-<http://tidal.com/>`_. It plays URLs in the form ``tidal://track/ID``,
-e.g.:
-
-.. warning::
-
-   This plugin is currently defunct because Tidal has changed the
-   protocol and decided not to share documentation.
-
-.. code-block:: none
-
-    mpc add tidal://track/59727857
-
-.. list-table::
-   :widths: 20 80
-   :header-rows: 1
-
-   * - Setting
-     - Description
-   * - **token TOKEN**
-     - The Tidal application token. Since Tidal is unwilling to assign a token to MPD, this needs to be reverse-engineered from another (approved) Tidal client.
-   * - **username USERNAME**
-     - The Tidal user name.
-   * - **password PASSWORD**
-     - The Tidal password.
-   * - **audioquality Q**
-     - The Tidal "audioquality" parameter. Possible values: HI_RES, LOSSLESS, HIGH, LOW. Default is HIGH.
-
 .. _decoder_plugins:
      
 Decoder plugins