Style guide issue: link to coding techniques for developing custom widgets

I suggest the style guide link to this page:
http://wiki.codetalks.org/wiki/index.php/Docs/Keyboard_navigable_JS_widgets

This will help authors who find their way to the style guide, but don't 
yet know how to implement the recommendations.

I've also added a link to the above implementation page to the DHTML style 
guide.

- Aaron