Quick typos in ffi-safe-polymorphism-in-rust

[RandomInsano]

Very helpful article! Thanks for writing it, clarified quite a few thoughts I had in my head.

Quick list of awkward phrasing for you:

• "The trick is works because"

Something I struggled to understand as well is where ::vtable:: comes from here:

            base: FileHandle::vtable::<W>(),

It's right after, but I thought I'd call it out as it confused me for a bit.

AND! There is in fact a thin_trait_object crate! I'm using it, but it has some things that need improving.