Doc: Rename `docandtoc' view script to `chapter'

Prepare that every chapter is displayed on a new page.

refs #4820

modules/doc/application/views/scripts/partials/chapter.phtml

@@ -0,0 +1 @@
+<?= $chapterHtml ?>

modules/doc/application/views/scripts/partials/docandtoc.phtml

@@ -1,20 +0,0 @@
-<h1><?= $docName ?> documentation</h1>
-<?php if ($docHtml === null): ?>
-<p>Documentation not available.</p>
-<?php else: ?>
-<div class="toc">
-<?= $this->partial(
-  'layout/menu.phtml',
-    'default',
-    array(
-      'items'   => $docToc->getChildren(),
-      'sub'     => false,
-      'url'     => ''
-    )
-  );
-?>
-</div>
-<div class="doc">
-<?= $docHtml ?>
-</div>
-<?php endif ?>