Link to LiteFS example app walkthrough 404s

[lucas-homer]

The LiteFS Overview page lists three guides and links to them. The second of three links, the example app walkthrough, links to a page that's missing. The index.html.md.erb file links to /docs/litefs/example but that file doesn't exist. This results in a 404 response.

[benbjohnson]

Thanks, @lucas-homer. I consolidated the Getting Started guide and the example application as there were a lot of similarities. I forgot the redirect though. I added that in #687 so /docs/litefs/example now redirects correctly.