doc: clarify the review and landing process

Adds/mentions:
- Link to glossary
- Commit squashing and CI run
- 48/72 hour wait and PR review feature
- Extra notes section
- "Landed in <sha>" comment

PR-URL: https://github.com/nodejs/node/pull/10202
Ref: https://github.com/nodejs/node/pull/10151


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>