Fix typo (yangshun#85)

Author: Joe Riggs

algorithms/bit-manipulation.md

@@ -2,6 +2,6 @@ Bit Manipulation
 ==
 
 - How do you verify if an interger is a power of 2?
-- Wirte a program to print the binary representation of an integer.
+- Write a program to print the binary representation of an integer.
 - Write a program to print out the number of 1 bits in a given integer.
-- Write a program to determine the largest possible integer using the same number of 1 bits in a given number.
+- Write a program to determine the largest possible integer using the same number of 1 bits in a given number.