Replaced soundness script with the official check

Fixes #97

.github/workflows/pull_request.yml

@@ -12,7 +12,6 @@ jobs:
       license_header_check_project_name: "Swift WebAuthn"
       shell_check_enabled: false
       format_check_enabled: false
-      license_header_check_enabled: false
       docs_check_enabled: false
 
   unit-tests:

.license_header_template

@@ -0,0 +1,12 @@
+@@===----------------------------------------------------------------------===@@
+@@
+@@ This source file is part of the Swift WebAuthn open source project
+@@
+@@ Copyright (c) YEARS the Swift WebAuthn project authors
+@@ Licensed under Apache License v2.0
+@@
+@@ See LICENSE.txt for license information
+@@
+@@ SPDX-License-Identifier: Apache-2.0
+@@
+@@===----------------------------------------------------------------------===@@

README.md

@@ -47,6 +47,13 @@ For an authentication ceremony use the following two methods:
 - `WebAuthnManager.beginAuthentication()`
 - `WebAuthnManager.finishAuthentication()`
 
+## Contributing
+
+If you add any new files, please run the following command at the root of the repo to identify any missing license headers:
+```bash
+% PROJECTNAME="Swift WebAuthn" /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/swiftlang/github-workflows/refs/heads/main/.github/workflows/scripts/check-license-header.sh)"
+```
+
 ## Credits
 
 Swift WebAuthn is heavily inspired by existing WebAuthn libraries like