Add custom-rendered page for amethyst crates keyword

[erlend-sh]

Could we be using crates.io as an API to display certain listings on our own website?

e.g. could we build a amethyst.rs/crates page that re-renders https://crates.io/keywords/amethyst?

Could be a handy way of going "looking for amethyst tooling? here's the current ecosystem".

Prior art:

• https://users.rust-lang.org/t/lib-rs-was-crates-rs-a-new-faster-crate-index-website/17876
• https://github.com/rust-lang/crates.io/wiki/Projects-that-use-crates.io%27s-API