Remove double punctuation

Even though it makes the code not exactly match what we entered,
completely

src/ch02-00-guessing-game-tutorial.md

@@ -679,7 +679,7 @@ Could not compile `guessing_game`.
 
 The core of the error states that there are *mismatched types*. Rust has a
 strong, static type system. However, it also has type inference. When we wrote
-`let mut guess = String::new();`, Rust was able to infer that `guess` should be
+`let mut guess = String::new()`, Rust was able to infer that `guess` should be
 a `String` and didn’t make us write the type. The `secret_number`, on the other
 hand, is a number type. A few number types can have a value between 1 and 100:
 `i32`, a 32-bit number; `u32`, an unsigned 32-bit number; `i64`, a 64-bit