console: Make baud an optional parameter

Make the baud rate an optional parameter to the console.py tool.  When
not present, it will default to 250000.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

docs/Debugging.md

@@ -123,12 +123,15 @@ possible to manually send these MCU commands (functions marked with
 the DECL_COMMAND() macro in the Klipper source code). To do so, run:
 
 ```
-~/klippy-env/bin/python ./klippy/console.py /tmp/pseudoserial 250000
+~/klippy-env/bin/python ./klippy/console.py /tmp/pseudoserial
 ```
 
 See the "HELP" command within the tool for more information on its
 functionality.
 
+Some command-line options are available. For more information run:
+`~/klippy-env/bin/python ./klippy/console.py --help`
+
 Generating load graphs
 ======================