Remove uninformative 'Further Reading' sections from rule docs

[hoonweiting]

Issue: #

What Changed

Some of the rules have a 'Further Reading' section that don't provide any additional reading materials. I simply removed them in this PR.

I considered modifying the template in generate-rule.ts too, but I can't think of a good way to do it since the writer will have to manually delete the section header anyway, if they have nothing to write for a given optional section.

Checklist

Check the ones applicable to your change:

• [ ] Ran yarn update-all
• [ ] Tests are updated
• [x] Documentation is updated

Change Type

Indicate the type of change your pull request is:

• [ ] maintenance
• [x] documentation
• [ ] patch
• [ ] minor
• [ ] major

[github-actions[bot]]

:rocket: PR was released in v0.9.0 :rocket: