Update footer with dynamic copyright year

Formatting

Author: mattt

_includes/footer.html

@@ -1,21 +1,36 @@
-    <div id="footer">
-      <div class="container">
-        <div class="row">
-          <div class="col-sm-3" id="about">
-            <p><strong class="logo">SwiftDoc.org</strong><br />
-            Auto-generated documentation for Swift. Command-click no more.</p>
-          </div>
-          <div class="col-sm-9" id="colophon">
-            <p>
-              <a href="/news/">News</a> &nbsp;&sdot;&nbsp;
-              <a href="https://twitter.com/{{ site.twitter_username }}">@{{ site.twitter_username }}</a> &nbsp;&sdot;&nbsp;
-              <a href="https://github.com/{{ site.github_username }}">github.com/{{ site.github_username }}</a><br />
-            </p>
-            <p>Created by parsing and analyzing the autogenerated header for the Swift standard library. Built using <a href="https://nodejs.org/en/">Node.js</a> and <a href="http://jekyllrb.com/">Jekyll</a>, hosted with <a href="https://netlify.com/">Netlify</a>.</p>
+<div id="footer">
+  <div class="container">
+    <div class="row">
+      <div class="col-sm-3" id="about">
+        <p>
+          <strong class="logo">SwiftDoc.org</strong><br />
+          Auto-generated documentation for Swift. Command-click no more.
+        </p>
+      </div>
+      <div class="col-sm-9" id="colophon">
+        <p>
+          <a href="/news/">News</a> &nbsp;&sdot;&nbsp;
+          <a href="https://twitter.com/{{ site.twitter_username }}"
+            >@{{ site.twitter_username }}</a
+          >
+          &nbsp;&sdot;&nbsp;
+          <a href="https://github.com/{{ site.github_username }}"
+            >github.com/{{ site.github_username }}</a
+          ><br />
+        </p>
+        <p>
+          Created by parsing and analyzing the autogenerated header for the
+          Swift standard library. Built using
+          <a href="https://github.com/swiftdocorg/swift-doc">SwiftDoc</a> and
+          <a href="http://jekyllrb.com/">Jekyll</a>, hosted with
+          <a href="https://netlify.com/">Netlify</a>.
+        </p>
 
-            <p>All content copyright © 2014–2018 Apple Inc. All rights reserved.</p>
-          </div>
-        </div>
+        <p>
+          All content copyright © 2014 – {{ site.time | date: '%Y' }} Apple Inc.
+          All rights reserved.
+        </p>
       </div>
     </div>
-
+  </div>
+</div>