README: Add note about pic16bit port.

README.md

@@ -44,6 +44,7 @@ Additional components:
   mostly to control code size.
 - teensy/ -- a version of Micro Python that runs on the Teensy 3.1
   (preliminary but functional).
+- pic16bit/ -- a version of Micro Python for 16-bit PIC microcontrollers.
 - unix-cpy/ -- a version of Micro Python that outputs bytecode (for testing).
 - tests/ -- test framework and test scripts.
 - tools/ -- various tools, including the pyboard.py module.