Fix a typo in the docs ("\true" => "\true\`")

Author: GrantJamesPowell

src/vector/mod.rs

@@ -673,7 +673,7 @@ impl<A: Clone> Vector<A> {
     /// Test if a given element is in the vector.
     ///
     /// Searches the vector for the first occurrence of a given value,
-    /// and returns `true if it's there. If it's nowhere to be found
+    /// and returns `true` if it's there. If it's nowhere to be found
     /// in the vector, it returns `false`.
     ///
     /// Time: O(n)