Correct note syntax for AsyncStream doc comments.

Author: Chris Adamson

stdlib/public/Concurrency/AsyncStream.swift

@@ -133,7 +133,7 @@ public struct AsyncStream<Element> {
       /// indicates the number of remaining slots in the buffer at the time of
       /// the `yield` call.
       ///
-      /// > Note: From a thread safety viewpoint, `remaining` is a lower bound
+      /// - Note: From a thread safety viewpoint, `remaining` is a lower bound
       /// on the number of remaining slots. This is because a subsequent call
       /// that uses the `remaining` value could race on the consumption of
       /// values from the stream.

stdlib/public/Concurrency/AsyncThrowingStream.swift

@@ -153,12 +153,14 @@ public struct AsyncThrowingStream<Element, Failure: Error> {
       ///
       /// This value reprsents the successful enqueueing of an element, whether
       /// the stream buffers the element or delivers it immediately to a pending
-      /// call to `next()`. The associated value `remaining` indicates the
-      /// number of remaining slots in the buffer at the point in time of
-      /// yielding.
+      /// call to `next()`. The associated value `remaining` is a hint that
+      /// indicates the number of remaining slots in the buffer at the time of
+      /// the `yield` call.
       ///
-      /// > Note: Acting on the remaining count is valid only when calls to
-      /// yield are mutually exclusive.
+      /// - Note: From a thread safety viewpoint, `remaining` is a lower bound
+      /// on the number of remaining slots. This is because a subsequent call
+      /// that uses the `remaining` value could race on the consumption of
+      /// values from the stream.
       case enqueued(remaining: Int)
 
       /// The stream didn't enqueue the element due to a full buffer.