Display the metadata section outside the the "main rectangle", to save space for the readme.

[wiiznokes]

When the web browser is in full screen, there is a lot of space wasted by this tiny section (in height). The the all readme, that can be long sometime. I noticed this on this crate: https://crates.io/crates/dirs.

I know it's not easy to design this, as all other tabs share the same layout. The first solution that came to me is display it always on the top, but i'm not sure if it will look good. Another solution could be to slip the markdown intelligently and use the full width for the second part.