Create nice index page

[kizu]

The default page shouldn't be an example one, but the one with the list of all available slides.

Also, a nice thing could be done: when there are no new custom slides, there should be links to examples, docs and some introduction/setup-like text, so when you'll clone the project for the first time you'll see all those example/placeholder things.

But if you'll add your custom slides, they would appear there replacing placeholder content (however, there should be some link to those content, like a small “tutorial” link at the bottom or something like this)