Remove `:crypto` application start from home page

Since [1][2], the `:crypto` application is included as a startup
dependency of Elixir.

[1]: https://github.com/elixir-lang/elixir/issues/2593

[2]: https://github.com/elixir-lang/elixir/commit/9ba77e1ce6d1ea346d01531385e22541933b4e58