Fixes copyright comment

rdar://78178197

Author: Kyle Macomber

stdlib/public/core/Sendable.swift

@@ -1,14 +1,14 @@
-////===----------------------------------------------------------------------===//
-////
-//// This source file is part of the Swift.org open source project
-////
-//// Copyright (c) 2021 Apple Inc. and the Swift project authors
-//// Licensed under Apache License v2.0 with Runtime Library Exception
-////
-//// See https://swift.org/LICENSE.txt for license information
-//// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
-////
-////===----------------------------------------------------------------------===//
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2021 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
 
 /// The Sendable protocol indicates that value of the given type can
 /// be safely used in concurrent code.