integrate cspell

[wasaga]

There are some spelling errors in the docs.
We should add cspell or other spell checker to the build.

i.e. see how Facebook's repo does that https://github.com/facebook/docusaurus/search?q=cspell

[calebdoxsey]

so many false positives. the word list will be very large.

[calebdoxsey]

it doesn't understand things like:

    Authorization: Basic cm9vdDpodW50ZXI0Mg==

I'm not sure how to provide an override without it showing up in the docs themselves, which we don't want.

[calebdoxsey]

turns out we can add directives to the front matter in md files

[desimone]

Should we add a precommit check to keep things pristine?