MDL-54046 enrol: Make docs urls match the old path

Previously each enrolment method had it's own url in the docs. Because of the
refactor in 3.1 all pages are now served from the same script. We need to
manually set the docs url so that it points to the old docs pages.

enrol/editinstance.php

@@ -42,6 +42,7 @@
 
 $PAGE->set_url('/enrol/editinstance.php', array('courseid' => $course->id, 'id' => $instanceid, 'type' => $type));
 $PAGE->set_pagelayout('admin');
+$PAGE->set_docs_path('enrol/' . $type . '/edit');
 
 if (empty($return)) {
     $return = new moodle_url('/enrol/instances.php', array('id' => $course->id));