This commit rewrites most of the documentation per rule and preset,
`remark-lint` itself, and `unified-lint-rule`.
* Better and more readable automatic examples
* Check and update all rule descriptions
* Use middot (·) and line-feed (␊) for relevant examples
* Unify descriptions of `'consistent`'
* Add some more docs where needed
Closes GH-158.
Previously, `remark-lint-list-item-spacing` worked by checking
if items were multine. Sometimes, you’d like to check if nodes
contain blank lines instead and base warnings on that.
With this new feature you can pass `{checkBlanks: true}` to opt
into checking for blanks.
Closes GH-144.
