Added readme.

src/main.rs

@@ -4,7 +4,7 @@ use std::fs::read_to_string;
 fn main() {
     let input = read_to_string("input/day01.txt").unwrap();
     println!("part1: {}", part1(&input));
-    println!("part1: {}", part2(&input));
+    println!("part2: {}", part2(&input));
 }
 
 type Int = i32;