Documentation tweaks

[SwiftsNamesake]

I was skimming the documentation and noticed a few minor typos. Would you accept a pull request that fixed them?

Thank you for an incredible library.

[Twinside]

Yes, I'd gladly accept it

[SwiftsNamesake]

Great, expect it within a few days. And thanks again.

[SwiftsNamesake]

I'm done. I'll go ahead and create a PR, although my editor tweaked the formatting slightly (stylish-haskell plugin).