Use multiple trailing closures in doc snippet.

Author: Chris Adamson

stdlib/public/Concurrency/AsyncStream.swift

@@ -286,13 +286,14 @@ public struct AsyncStream<Element> {
   /// iteration).
   ///
   /// The following example shows an `AsyncStream` created with this
-  /// initializer that produces random numbers on a one-second interval.
+  /// initializer that produces random numbers on a one-second interval. This
+  /// example uses Swift's multiple trailing closure syntax, which omits
+  /// the `unfolding` parameter label.
   ///
-  ///     let stream = AsyncStream<Int>(
-  ///         unfolding: {
+  ///     let stream = AsyncStream<Int> {
   ///             await Task.sleep(1 * 1_000_000_000)
   ///             return Int.random(in: 1...10)
-  ///         },
+  ///         }
   ///         onCancel: { @Sendable () in print ("Canceled.") }
   ///     )
   ///

stdlib/public/Concurrency/AsyncThrowingStream.swift

@@ -327,7 +327,7 @@ public struct AsyncThrowingStream<Element, Failure: Error> {
   /// The following example shows an `AsyncThrowingStream` created with this
   /// initializer that produces random numbers on a one-second interval. If the
   /// random number is divisble by 5 with no remainder, the stream throws a
-  ///  `MyRandomNumberError`.
+  /// `MyRandomNumberError`.
   ///
   ///     let stream = AsyncThrowingStream<Int, Error> {
   ///             await Task.sleep(1 * 1_000_000_000)