got rid of some comments and added support for 3 shift chips

-/*
- * SN74HC165N_shift_reg
- *
- * Program to shift in the bit values from a SN74HC165N 8-bit
- * parallel-in/serial-out shift register.
- *
- * This sketch demonstrates reading in 16 digital states from a
- * pair of daisy-chained SN74HC165N shift registers while using
- * only 4 digital pins on the Arduino.
- *
- * You can daisy-chain these chips by connecting the serial-out
- * (Q7 pin) on one shift register to the serial-in (Ds pin) of
- * the other.
- *
- * Of course you can daisy chain as many as you like while still
- * using only 4 Arduino pins (though you would have to process
- * them 4 at a time into separate unsigned long variables).
- *
-*/
added images and arduino circut image