Update header.

hello_world/firmware/main.c

@@ -1,3 +1,15 @@
+/*
+ * Hello world of AVR. Blink led PORTB5 (Arduino digital 13).
+ *
+ * To compile and upload run: make clean; make; make program;
+ *
+ * Copyright 2009-2011 Mika Tuupola
+ *
+ * Licensed under the MIT license:
+ *   http://www.opensource.org/licenses/mit-license.php
+ *
+ */
+ 
 #include <avr/io.h>
 #include <util/delay.h>