Add Cookbook tutorial for changing sidebar menus for each section

[GoogleCodeExporter]

Originally, it was brute force with a different template for each section. 
We're in the middle of switching over to using page attributes to include 
different menus for different sections. So the is a page attribute "sidebar", 
which is set at the root, and then at the parent for each page section. Sidebar 
indicates another content entry to include for the menu code. 

</div>
$service.findContent($page.attribute.sidebar)
<div ...

Original issue reported on code.google.com by ted.husted on 17 Dec 2010 at 4:17

• Blocked on: #403

[GoogleCodeExporter]

Original comment by ted.husted on 26 Dec 2010 at 2:22