{cc3200,nrf}/boards/make-pins.py: Add a note about tools/boardgen.py.

It's not worth the effort to update these ports to use boardgen.py, but
put a note just in case anyone uses this as a reference for a new port.

This work was funded through GitHub Sponsors.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

ports/cc3200/boards/make-pins.py

 #!/usr/bin/env python
 """Generates the pins file for the CC3200."""
 
+# Do not use this as a reference for new ports. See tools/boardgen.py and e.g.
+# ports/stm32/boards/make-pins.py.
+
 from __future__ import print_function
 
 import argparse

ports/nrf/boards/make-pins.py

 #!/usr/bin/env python
 """Creates the pin file for the nRF5."""
 
+# Do not use this as a reference for new ports. See tools/boardgen.py and e.g.
+# ports/stm32/boards/make-pins.py.
+
 from __future__ import print_function
 
 import argparse