Removed auto as a hardware synth device option. It was too flakey.

README.md

@@ -467,8 +467,7 @@ setting <action> [parameters]
 USB hardware synths are supported only when Linux exposes them as a serial tty
 such as `/dev/ttyACM0` or `/dev/ttyUSB0`. A USB-only TripleTalk with no tty
 device would require a separate USB protocol driver. Use an explicit
-`speech#hardware_device` path for stable hardware speech; `auto` is limited to
-devices that respond to a driver-specific probe.
+`speech#hardware_device` path for hardware speech.
 - `speech#auto_read_incoming=True/False` - Auto-read new text
 
 *Sound Settings:*