Add LICENSE (CERN OHL 1.2)

README.md

@@ -1,3 +1,8 @@
 # dryer-buzz-pcb
 
-Hardware for the dryer buzz detector
+Hardware for the dryer buzz detector
+
+## License
+
+dryer-buzz-pcb is Copyright (C) 2018 Clayton G. Hobbs, and made available under
+the CERN Open Hardware Licence v1.2.  See LICENSE for more information.