docs: add a Presidio sample for AISIX AI Gateway

[Yilialinn]

Change Description

Add a self-contained documentation sample showing how to use Presidio Analyzer and Anonymizer as an input guardrail for the open-source AISIX AI Gateway.

The sample covers:

• starting the two Presidio services with pinned images;
• configuring per-entity masking and blocking in AISIX;
• attaching the guardrail so it applies to gateway traffic;
• verifying anonymization, blocking, and fail-closed behavior; and
• keeping the unauthenticated Presidio endpoints on a private network.

It also adds the sample to the documentation index and navigation. This is a documentation-only contribution and changes no Presidio runtime behavior.

Validation completed with AISIX 1.2.0 and Presidio 2.2.364 against a local mock provider. Email masking, SSN blocking, and fail-closed behavior were reproduced. The repository's Zensical documentation build also passed locally.

Disclosure: I work at API7.ai, which maintains AISIX. AISIX is an Apache-2.0-licensed independent open-source project and is not an Apache Software Foundation project.

Issue reference

N/A — the contribution guide accepts self-contained samples directly.

Checklist

• I have reviewed the contribution guidelines
• I agree to follow this project's Code of Conduct
• I confirm that I have the right to submit this contribution and that it does not knowingly contain proprietary or confidential code.
• My code includes unit tests — Not applicable; this is a documentation-only change.
• All unit tests and lint checks pass locally — Not applicable; no runtime code changed. The documentation build passed locally.
• My PR contains documentation updates / additions if required

[Copilot]

🟢 Approval recommended

The documentation changes were fully reviewed and have no unresolved blocking issues.

Pull request overview

Adds a self-contained documentation sample integrating Presidio with AISIX AI Gateway for PII masking, blocking, and fail-closed behavior.

Changes:

• Adds AISIX and Presidio setup instructions.
• Documents verification and private networking.
• Updates the samples index and navigation.

File summaries

File	Summary
mkdocs.yml	Adds the sample to documentation navigation.
docs/samples/index.md	Adds the sample to the index.
docs/samples/docker/aisix.md	Adds the AISIX integration guide.

Review details

• Files reviewed: 3/3 changed files
• Comments generated: 0
• Review effort level: Lite

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[omri374]

Thanks!