shorten range syntax

Author: web-flow

src/libcollections/btree/set.rs

@@ -227,7 +227,7 @@ impl<T: Ord> BTreeSet<T> {
     /// for &elem in set.range((Included(&4), Included(&8))) {
     ///     println!("{}", elem);
     /// }
-    /// assert_eq!(Some(&5), set.range((Included(&4), Unbounded)).next());
+    /// assert_eq!(Some(&5), set.range(4..).next());
     /// ```
     #[unstable(feature = "btree_range",
                reason = "matches collection reform specification, waiting for dust to settle",