doc: it is 'index', not 'i'

tshepang · steveklabnik · commit 40fe325037eb · 2015-05-10T15:19:32.000-04:00
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
@@ -540,7 +540,7 @@ impl<T> Vec<T> {
     ///
     /// # Panics
     ///
-    /// Panics if `i` is out of bounds.
+    /// Panics if `index` is out of bounds.
     ///
     /// # Examples
     ///
