Rack attack initializer docs whitelist>allowlist blacklist>denylist

Problem

Rack Attack initializer (source) documentation uses outdated and politically incorrect terms "whitelist" and "blacklist" which indicate color but not functionality.

Proposal

Change occurrences of the term "blacklist" to "denylist" and "whitelist" to "allowlist".

Why?

The new terms describe functionality and are superior to the old terms.