Remove TOC from README

[davereid]

We should have an automated way to catch if the README.md file is updated with new headings, but the automatic DocToc table of contents hasn't been changed.

Or alternatively, we could have a workflow that automatically adds a commit to the PR that fixes it automatically. https://github.com/marketplace/actions/toc-generator could potentially be used for this, but we would need to provide a GITHUB_TOKEN that is generated using our GitHub app so that workflows will run after the commit.

[justafish]

GitHub has got a table of contents built in so maybe we don't need it at all?

https://docs.github.com/en/repositories/managing-your-repositorys-settings-and-features/customizing-your-repository/about-readmes#auto-generated-table-of-contents-for-readme-files

[deviantintegral]

Wow, that's totally new, and awesome! I'm fine with that, and teams using GitLab or Bitbucket can make their own decisions.