MDL-39366 book: Section appearance in book module settings

mod/book/mod_form.php

@@ -47,6 +47,9 @@ class mod_book_mod_form extends moodleform_mod {
         $mform->addRule('name', null, 'required', null, 'client');
         $this->add_intro_editor($config->requiremodintro, get_string('moduleintro'));
 
+        // Appearance.
+        $mform->addElement('header', 'appearancehdr', get_string('appearance'));
+
         $alloptions = book_get_numbering_types();
         $allowed = explode(',', $config->numberingoptions);
         $options = array();