Move style of div.wrap to internal style sheet.
Add products/index page.
Add a helper method to generate links.
Adjust the style.
Add breadcrumbs.
Add a helper method to generate breadcrumbs.
Add the div.breadcrumbs in the website layout.
Set breadcrumbs via content_for in products pages and docs pages.
Update the css in products/index page because the breadcrumbs change the
order of html elements.
Add title_starts_with method.
Add ":letter" to products/category route.
Filter products by letter unless letter is blank.
Update the title-letter-nav.