Add missing closing parenthesis

Author: joshlf

core/src/num/nonzero.rs

@@ -37,7 +37,7 @@ macro_rules! nonzero_integers {
             ///
             /// # Layout
             ///
-            #[doc = concat!("`", stringify!($Ty), "` is guaranteed to have the same layout and bit validity as `", stringify!($Int), "`"]
+            #[doc = concat!("`", stringify!($Ty), "` is guaranteed to have the same layout and bit validity as `", stringify!($Int), "`")]
             /// with the exception that `0` is not a valid instance.
             #[$stability]
             #[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]