crates.io -> lib.rs

Replace all links to crates.io with ones to lib.rs, as the latter is much faster because it doesn't use tons of JavaScript

Versión del día 5/4/2020. Echa un vistazo a la versión más reciente.

Replace all links to crates' pages on crates.io with ones to lib.rs, as the latter is much faster because it doesn't use tons of JavaScript