Docusaurus: Integrate prettier into our PR workflow

[ericnakagawa]

Let's standardize on a single prettier config so we can... move fast!

[roryokane]

It looks like this issue can be closed: there is a .prettierrc, there are package.json scripts that use Prettier, and CircleCI is running the ci-check script.

[prescottprue]

Might also be nice to use something like husky to add a prepush hook that runs npm run prettier. That way lint can be caught before pushing as opposed to through the CI build failing.

[JoelMarcey]

@prescottprue Yes, I think that was part of the creation of this issue too, because you are right, we catch the failures after we push and thus have to patch with an updated fix if there is a failure.