build fix

oops https://travis-ci.org/rust-lang-nursery/reference/builds/357767981

Author: steveklabnik

src/expressions/match-expr.md

@@ -147,7 +147,7 @@ let arr = [1, 2, 3];
 match arr {
     [1, _, _] => "starts with one",
     [a, b, c] => "starts with something else",
-}
+};
 ```
 ```rust
 // Dynamic size