Alter formatting for words in Option::cloned doc comment

src/libcore/option.rs

@@ -706,7 +706,8 @@ pub fn as_slice(&self) -> &[T] {
 }
 
 impl<'a, T: Clone> Option<&'a T> {
-    /// Maps an Option<&T> to an Option<T> by cloning the contents of the Option.
+    /// Maps an `Option<&T>` to an `Option<T>` by cloning the contents of the
+    /// option.
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn cloned(self) -> Option<T> {
         self.map(|t| t.clone())