Document that Ordering::Relaxed is Monotonic

Author: sorear

src/libcore/sync/atomic.rs

@@ -153,7 +153,8 @@ unsafe impl<T> Sync for AtomicPtr<T> {}
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Copy, Clone)]
 pub enum Ordering {
-    /// No ordering constraints, only atomic operations.
+    /// No ordering constraints, only atomic operations. Corresponds to LLVM's
+    /// `Monotonic` ordering.
     #[stable(feature = "rust1", since = "1.0.0")]
     Relaxed,
     /// When coupled with a store, all previous writes become visible