docs/system/replay: do not show removed command line option

Cc: qemu-trivial@nongnu.org
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs/system/replay.rst

@@ -181,7 +181,7 @@ Audio data is recorded and replay automatically. The command line for recording
 and replaying must contain identical specifications of audio hardware, e.g.:
 
 .. parsed-literal::
-    -soundhw ac97
+    -audio pa,model=ac97
 
 Serial ports
 ------------