RS 8.0.20 release docs

[rrelledge]

Release notes staged preview: https://redis.io/docs/staging/DOC-6419/operate/rs/release-notes/rs-8-0-releases/rs-8-0-20-16/

TODO:

1. Add checksums when available

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Note

Low Risk
Docs-only changes that add new release documentation and reference-field updates; no product code or runtime behavior is modified.

Overview
Adds a new Redis Software 8.0.20-16 release-notes page highlighting LDAP certificate-based authentication, Amazon Linux 2023 support, and various API/metrics documentation updates.

Updates reference docs to reflect new/expanded fields and outputs: new Redis Search Prometheus metrics, Amazon Linux 2023 in supported platforms, rladmin status extra option for manually stopped traffic, new traffic_manually_disabled BDB field, new CRDT-supported mapping fields and external auth toggles in the cluster object, and new LDAP CBA-related fields. Also adds a dedicated how-to page for LDAP certificate-based authentication setup.

^{Reviewed by Cursor Bugbot for commit 467885b. Bugbot is set up for automated code reviews on this repo. Configure here.}

[github-actions]

DOC-6419

[github-actions]

Staging links:
https://redis.io/docs/staging/DOC-6419/operate/rs/references/cli-utilities/rladmin/status/
https://redis.io/docs/staging/DOC-6419/operate/rs/references/rest-api/objects/bdb/
https://redis.io/docs/staging/DOC-6419/operate/rs/references/rest-api/objects/cluster/
https://redis.io/docs/staging/DOC-6419/operate/rs/references/rest-api/objects/ldap/
https://redis.io/docs/staging/DOC-6419/operate/rs/release-notes/rs-8-0-releases/rs-8-0-20-16/
https://redis.io/docs/staging/DOC-6419/operate/rs/security/access-control/ldap/certificate-based-authentication/

[jit-ci]

🛡️ Jit Security Scan Results

✅ No security findings were detected in this PR

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^{Security scan by Jit}