Update README.md

Fixed a typo.

Author: drbrowen

README.md

@@ -9,7 +9,7 @@ LED strips 15 across, back and forth.  The LEDs are numberd as follows:
 Row 0:  0  1  2  3  4  5  6  7  8  9 10 11 12 13 14
 Row 1: 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15
 Row 2: 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
-Ro2 4: 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45
+Ro2 3: 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45
 </pre>
 etc.