Fix usage of code-prettify in documentation (#423)

This fixes regression introduced in 0.7.7
by commit 8bc34b18bc5a0b53a94859089c876740c82cec5c
diff --git a/org.jacoco.doc/docroot/doc/implementation.html b/org.jacoco.doc/docroot/doc/implementation.html
index 72175d5..3f4994a 100644
--- a/org.jacoco.doc/docroot/doc/implementation.html
+++ b/org.jacoco.doc/docroot/doc/implementation.html
@@ -4,9 +4,9 @@
 <head>
   <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
   <link rel="stylesheet" href=".resources/doc.css" charset="UTF-8" type="text/css" />
-  <link rel="stylesheet" href="../coverage/.resources/prettify.css" charset="UTF-8" type="text/css" />
+  <link rel="stylesheet" href="../coverage/jacoco-resources/prettify.css" charset="UTF-8" type="text/css" />
   <link rel="shortcut icon" href=".resources/report.gif" type="image/gif" />
-  <script type="text/javascript" src="../coverage/.resources/prettify.js"></script>
+  <script type="text/javascript" src="../coverage/jacoco-resources/prettify.js"></script>
   <title>JaCoCo - Implementation Design</title>
 </head>
 <body onload="prettyPrint()">