std::any's documentation should use dyn

[0xrgb]

https://doc.rust-lang.org/std/any/index.html
https://doc.rust-lang.org/std/any/trait.Any.html

Newcomers who learn rust with rust book 2018 edition can be confused, because official book recommends &dyn TraitObject and does not say about &TraitObject.

[Centril]

@0xrgb I think a PR fixing this would be welcome. :)