Docs: Describe options in rules under Possible Errors part 2

[pedrottimark]

The next 10 rules under Possible Errors

• Make description in h1 consistent with rules index page, not even the first word is capitalized. That is because will soon change the format to match the rules index page (that is, rule-id: rule description).
• Make first sentence under Rule Details consistent with description.
• Add “this rule with” to example sentences.
• Describe options according to patterns in guidelines.

Here are additional changes:

• no-empty-character-class: add Known Limitations; delete Related Rules link to removed rule
• no-ex-assign: make examples parallel
• no-extra-parens: add links to rules with potential conflicts which are ignored
• no-irregular-whitespace: move examples from Rule Details to Options; change indent from 2 to 4
• no-negated-in-lhs: rewrite introduction with analogy to incorrect numerical negation; remove Further Reading

[eslintbot]

LGTM

[mention-bot]

By analyzing the blame information on this pull request, we identified @IanVS, @michaelficarra and @rhysd to be potential reviewers

[rhysd]

LGTM for no-irregular-whitespace rule.

[ilyavolodin]

LGTM