Update date.

whatsnew.htm

@@ -26,7 +26,7 @@ Portions Copyright &copy; 2000-2018 Martijn Laan. All rights reserved.<br />
 For conditions of distribution and use, see <a href="http://www.jrsoftware.org/files/is/license.txt">LICENSE.TXT</a>.
 </p>
 
-<p><a name="5.6.0"></a><span class="ver">5.6.0 </span><span class="date">(?)</span></p>
+<p><a name="5.6.0"></a><span class="ver">5.6.0 </span><span class="date">(2018-06-08)</span></p>
 <ul>
 <li>/LOG: Now logs registry entries.</li>
 <li>Compiler IDE change: Syntax highlighting and syntax error underlining support for <tt>#include</tt> and ISPP has been significantly improved (with ISPP installed: <a href="https://i.imgur.com/nPiun9k.png">before</a> and <a href="https://i.imgur.com/HoJaBRP.png">after</a>, without ISPP installed: <a href="https://i.imgur.com/nPiun9k.png">before</a> and <a href="https://i.imgur.com/ro0ejL3.png">after</a></li>