Remove a paragraph about the old socket option

doc/src/guide/listeners.asciidoc

@@ -172,13 +172,6 @@ The custom `listen/1` function must ensure that the listener process
 of the socket it returns. Failing to do so will result in stop/start
 and suspend/resume not working properly for that listener.
 
-While it might be tempting to pass in an existing socket to your
-custom transport by way of the transport options, thereby mimicking
-a deprecated ranch behavior, this is considered dangerous and was removed
-for that very reason. In general, it should be ensured that the socket
-to be returned from a custom `listen/1` function really is a listening
-socket and that it is operational.
-
 === Limiting the number of concurrent connections
 
 The `max_connections` transport option allows you to limit the number