DocParser: remove explicit call to getRelativeUrl

As this URLs will get rendered we want them to be automatically casted
resulting in correct URLs with &

refs #6699

modules/doc/library/Doc/DocParser.php

@@ -109,7 +109,7 @@ class DocParser
                                 array(
                                     'name' => $this->module
                                 )
-                            )->setAnchor($id)->getRelativeUrl(),
+                            )->setAnchor($id),
                             'title'     => htmlspecialchars($header),
                             'priority'  => $itemPriority++,
                             'attribs'   => $attribs