fix license headers

Author: ktoso

BuildLogic/src/main/kotlin/build-logic.java-library-conventions.gradle.kts

@@ -6,6 +6,7 @@
 // Licensed under Apache License v2.0
 //
 // See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
 //
 // SPDX-License-Identifier: Apache-2.0
 //

JavaSwiftKitDemo/src/main/java/com/example/swift/HelloSubclass.java

@@ -6,6 +6,7 @@
 // Licensed under Apache License v2.0
 //
 // See LICENSE.txt for license information
+// See CONTRIBUTORS.txt for the list of Swift.org project authors
 //
 // SPDX-License-Identifier: Apache-2.0
 //