docs: add typos in a tab, use it for our checking

[henryiii]

We've included it in sp-repo-review's checks as an alternative for quite a while, but after @mikeckennedy brought it up on Python Bytes, I though we could add it as a tab (we recently added support for multiple unrelated tab sets on a page). It found a few typos locally that codespell didn't, so happy about that. Doesn't seem to ship to PyPI, which is a minor downside, but not too bad. It's fast (though codespell is too).

I'll try it on a few more repos over time, and will switch the template to use it if it continues to work well. Like any linter switch, it's hard to tell if it would have caught everything that the old tool caught, but catching more is a good sign.

Brought up an issue in the docs in crate-ci/typos#1441, an option that would have been a little nicer / more similar to codespell but doesn't seem to exist.

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