chore: remove guardrails example plugin

[afourniernv]

Overview

Remove the old NeMo Guardrails example plugin from examples/ and clean up the remaining docs and test references to that deprecated example surface.

• I confirm this contribution is my own work, or I have the right to submit it under this project's license.
• I searched existing issues and open pull requests, and this does not duplicate existing work.

Details

This PR:

• removes examples/nemoguardrails and its bundled agent/example assets
• removes the dedicated Python test for the example plugin
• deletes the old docs/build-plugins/nemoguardrails.mdx page
• trims the last Build Plugins docs link that pointed to the removed example page
• removes obsolete Fern cleanup rewrite rules that referenced the deleted example files

Validation:

• uv run pre-commit run --files docs/build-plugins/about.mdx scripts/docs/fern_cleanup.py docs/build-plugins/nemoguardrails.mdx examples/nemoguardrails/README.md examples/nemoguardrails/example/agent_example.py examples/nemoguardrails/example/example_config.yml examples/nemoguardrails/example/plugin.py examples/nemoguardrails/example/rails/config.yml python/tests/test_nemoguardrails_example_plugin.py
• uv run pre-commit run --all-files

Pre-commit caveat:

• full pre-commit only failed docs markdown linkcheck because this environment could not reach several external public URLs; the cleanup branch did not leave any example-plugin references behind

Where should the reviewer start?

Start with:

• docs/build-plugins/about.mdx
• scripts/docs/fern_cleanup.py
• the deleted examples/nemoguardrails tree

Related Issues: (use one of the action keywords Closes / Fixes / Resolves / Relates to)

• Relates to: none

[copy-pr-bot]

This pull request requires additional validation before any workflows can run on NVIDIA's runners.

Pull request vetters can view their responsibilities here.

Contributors can view more details about this message here.

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: ASSERTIVE

Plan: Enterprise

Run ID: 1bc6c402-e7e9-428b-b1ce-5cfdd00e7171

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}