Add renaming advice based on IETF draft-knodel-terminology-00 (#1556)

* Add renaming advice based on IETF draft-knodel-terminology-00

Add a new "usage" dictionary with usage advice based on:
https://tools.ietf.org/id/draft-knodel-terminology-00.html#rfc.section.1.1.1

Offer to replace master/slave with:
- Primary-secondary
- Leader-follower
- Active-standby
- Primary-replica
- Writer-reader
- Coordinator-worker
- Parent-helper

* Move recommended terms to "usage" dictionary

Backout the changes from commit 98ab0fa and move them into the
"usage" dictionary.

* Fix use of "whitelist" in README

Use the recommended replacement "allowlist"

* Update codespell_lib/_codespell.py

Co-authored-by: Eric Larson <larson.eric.d@gmail.com>