Add examples for iter::range_step

Author: steveklabnik

src/libcore/iter.rs

@@ -2592,7 +2592,29 @@ pub struct RangeStep<A> {
     rev: bool,
 }
 
-/// Return an iterator over the range [start, stop) by `step`. It handles overflow by stopping.
+/// Return an iterator over the range [start, stop) by `step`.
+///
+/// It handles overflow by stopping.
+///
+/// # Examples
+///
+/// ```
+/// use std::iter::range_step;
+///
+/// for i in range_step(0, 10, 2) {
+///     println!("{}", i);
+/// }
+/// ```
+///
+/// This prints:
+///
+/// ```text
+/// 0
+/// 2
+/// 4
+/// 6
+/// 8
+/// ```
 #[inline]
 #[unstable(feature = "core",
            reason = "likely to be replaced by range notation and adapters")]
@@ -2633,7 +2655,30 @@ pub struct RangeStepInclusive<A> {
     done: bool,
 }
 
-/// Return an iterator over the range [start, stop] by `step`. It handles overflow by stopping.
+/// Return an iterator over the range [start, stop] by `step`.
+///
+/// It handles overflow by stopping.
+///
+/// # Examples
+///
+/// ```
+/// use std::iter::range_step_inclusive;
+///
+/// for i in range_step_inclusive(0, 10, 2) {
+///     println!("{}", i);
+/// }
+/// ```
+///
+/// This prints:
+///
+/// ```text
+/// 0
+/// 2
+/// 4
+/// 6
+/// 8
+/// 10
+/// ```
 #[inline]
 #[unstable(feature = "core",
            reason = "likely to be replaced by range notation and adapters")]