docs(config): note that the mpris setting covers all media integration

The JSON key stays 'mpris' for backwards compatibility, but it now also
governs the macOS Now Playing session and the media keys.

somafm_tui/config.py

@@ -72,6 +72,9 @@ class Config:
     volume: int = 70
     visualizer: str = "both"
     autoplay: bool = False
+    #: Publish what is playing to the desktop media session (MPRIS on Linux,
+    #: macOS Now Playing via mpv) and honour the media keys.  The JSON key is
+    #: spelled ``mpris`` for backwards compatibility.
     mpris: bool = True
 
     @classmethod