Match the Swift.org footer (#88)

This uses the same custom template that the docs for DocC use.

Fixes rdar://103026794

Author: amartini51

TSPL.docc/footer.html

@@ -0,0 +1,28 @@
+<!--
+This source file is part of the Swift.org open source project
+
+Copyright (c) 2014 - 2022 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
+-->
+
+<script src="https://swift.org/assets/javascripts/docc/footer.js"></script>
+<footer id="footer" role="contentinfo" hidden>
+  <div class="container">
+    <div>
+      <p class="copyright">Copyright © 2014 &en; 2023 Apple Inc. and the Swift project authors. All rights reserved.</p>
+      <p>This document is made available under a <a rel="license" href="https://creativecommons.org/licenses/by/4.0/" style="color: #09f">Creative Commons Attribution 4.0 International (CC BY 4.0) License</a>.</p>
+      <p class="trademark">Swift and the Swift logo are trademarks of Apple Inc.</p>
+      <p class="privacy">
+        <a href="//www.apple.com/privacy/privacy-policy/">Privacy Policy</a>
+        <a href="//www.apple.com/legal/privacy/en-ww/cookies/">Cookies</a>
+      </p>
+    </div>
+    <aside>
+      <a href="/atom.xml" title="Subscribe to Site Updates"><i class="feed"></i></a>
+      <a href="https://twitter.com/swiftlang" rel="nofollow" title="Follow @SwiftLang on Twitter"><i class="twitter"></i></a>
+    </aside>
+  </div>
+</footer>