doc: space around lists

Address markdownlint rule MD032.
Flagged a few mixed list styles.

PR-URL: https://github.com/nodejs/node/pull/29467


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>