Minor - Update release date in changelog

Author: ywarnier

documentation/changelog.html

@@ -109,7 +109,7 @@ <h1>Chamilo&nbsp;Changelog</h1>
     <div class="version" aria-role="article" aria-label="1.11.8">
     <a name="1.11.8"></a>
 
-    <h1>Chamilo 1.11.8 - Sayaxché,  12/08/2018</h1>
+    <h1>Chamilo 1.11.8 - Sayaxché,  13/08/2018</h1>
     <h3>Release notes - summary</h3>
     <p>Chamilo 1.11.8 is a minor, bug fix and security fix release on top of 1.11.6 that contains a series of
         small new features, including first support for European RGPD. Given the security fixes it contains,