update years in all copyright messages (one more)

Author: rse

features.html

@@ -77,7 +77,7 @@
         </div>
         <div class="foot">
             <div class="text">
-                Copyright &copy; 2015 <a href="http://engelschall.com/">Ralf S. Engelschall</a> &nbsp; <i class="fa fa-twitter-square"></i> <a href="http://twitter.com/engelschall">@engelschall</a><br/>
+                Copyright &copy; 2015-2016 <a href="http://engelschall.com/">Ralf S. Engelschall</a> &nbsp; <i class="fa fa-twitter-square"></i> <a href="http://twitter.com/engelschall">@engelschall</a><br/>
                 Fully generated from a <a href="https://github.com/rse/es6-features/blob/gh-pages/features.txt">single source</a><br/>
                 Licensed under <a href="https://github.com/rse/es6-features/blob/gh-pages/LICENSE.txt">MIT License</a>.
             </div>