fix doc

Author: s-light

nonblocking_serialinput.py

@@ -24,11 +24,8 @@
 * Adafruit CircuitPython firmware for the supported boards:
   https://github.com/adafruit/circuitpython/releases
 
-.. todo:: Uncomment or remove the Bus Device and/or the Register library dependencies
-  based on the library's use of either.
-
-# * Adafruit's Bus Device library: https://github.com/adafruit/Adafruit_CircuitPython_BusDevice
-# * Adafruit's Register library: https://github.com/adafruit/Adafruit_CircuitPython_Register
+* Core Module usb_cdc:
+  https://circuitpython.readthedocs.io/en/latest/shared-bindings/usb_cdc/index.html
 """
 
 # imports