docs: update NGINX to v2.23.1

[Qamar254]

Proposed changes

Changes w.r.t NIM patch release 2.23.1

-- NIM version bumped up to 2.23.1
-- Support for NGINX-OSS 1.31.6

Checklist

Before sharing this pull request, I completed the following checklist:

• I read the Contributing guidelines
• My branch adheres to the Git conventions
• My content changes adhere to the F5 Technical Writing Style Guide
• If my changes involve potentially sensitive information¹, I have assessed the possible impact
• I have waited to ensure my changes pass tests, and addressed any discovered issues

Footnotes

1. Potentially sensitive information includes personally identify information (PII), authentication credentials, and live URLs. Refer to the style guide for guidance about placeholder content. ↩

[github-actions]

✅ All required contributors have signed the F5 CLA for this PR. Thank you!
_{Posted by the CLA Assistant Lite bot.}

[promptless]

Thanks for keeping the compatibility tables current, @Qamar254 — this is a clean, tightly scoped version bump. I reviewed it against the F5 Technical Writing Style Guide, the same check GitHub Copilot runs before a writer picks it up.

Style review: no findings

The changes are data only — table cells and Docker Compose image tags — so no prose changed. The new rows match the format of the surrounding content, and the version ranges keep the en-dash range convention (2.21.0–2.23.1, 1.18–1.31.6), consistent with numbers and hyphens. Table structure and headers are unchanged.

Because nothing prose-facing changed, the reading-level and voice topics don't apply to this diff.

Technical accuracy — please have a subject matter expert verify

I flag these rather than correct them, and none block the style review:

1. NIM 2.23.1 doesn't appear to be released yet. The public release-notes index lists 2.23.0 as the latest, and a 2.23.1-release-notes page isn't live. Please confirm 2.23.1 has shipped publicly before these tables and image tags present it as available — the repository's contribution etiquette asks us not to document a version until it's public. This affects the chart row, the F5 WAF support row, and both docker-compose image tags.
2. NGINX Open Source range extended to 1.31.6 in supported-nginx-versions.md. NGINX OSS 1.31.6 (mainline) is published, so the version is real. Please confirm NIM 2.18.0+ is actually qualified up to 1.31.6, rather than 1.31.6 simply being the newest upstream release.
3. New chart row 2.3.1 / nginx-stable/nim / 2.23.1 and the F5 WAF support row now 2.21.0–2.23.1. Please confirm the chart version (2.3.1) and the F5 WAF release compatibility both hold for NIM 2.23.1.

Systematic topic check

• Checked in full: voice-and-tone and grammar (per the mandatory check — no prose in the diff for them to apply to); punctuation, formatting (tables, numbers, hyphens, dates-and-times), procedures, and terminology (f5-product-names, word-list).
• Checked, relevant: sensitive-information — the image reference uses the documented private-registry.nginx.com host and the diff contains no sensitive data.
• Skipped: accessibility, media, and error-messages — no images, media, or error strings in the diff.

The merge decision is the maintainer's; I'm leaving this as a comment so the version facts above can be confirmed first.

[Qamar254]

I have hereby read the F5 CLA and agree to its terms

[promptless]

This PR updates the NGINX Instance Manager compatibility tables and Docker Compose files for the 2.23.1 patch: it adds the 2.3.1 Helm chart row, extends the F5 WAF for NGINX support range to 2.23.1, raises the supported NGINX Open Source ceiling to 1.31.6, and bumps the Compose image tags to 2.23.1.

No style findings.

Technical accuracy, to confirm with a subject matter expert:

1. The tables now list NGINX Instance Manager 2.23.1 as a supported version, but no 2.23.1 release notes page exists yet. https://docs.nginx.com/nginx-instance-manager/releases/2.23.1-release-notes/ returns 404, and the release notes index still ends at 2.23.0. Confirm that 2.23.1 has shipped, and whether a 2.23.1 release notes page should publish alongside these compatibility updates.