Update README

README

@@ -1,4 +1,4 @@
-# USART Commands
+## Serial Interface
 
 Instead of polling for input we use an interrupt vector
 to write data to a rx ring buffer when it's available.
@@ -6,3 +6,16 @@ to write data to a rx ring buffer when it's available.
 We parse commands using a state machine so we can deal
 with small chunks of characters at a time and spit out
 the parsed command when the transmission has finished.
+
+TODO: Do we need to handle backspaces for interactive
+serial consoles?!
+
+### Supported Commands
+
+Optional decimal point for numbers.
+
+- START
+- RESET
+- STOP
+- SET TEMP 20.0
+- SET DEWP 60.0