[product-manager-impersonator] Render alternate workflow examples in docs

## Feature Idea

**Summary:** Update the generated workflow docs so pages automatically include alternate example files such as `example-chained.yml` when a workflow ships them, instead of showing only the detector-only `example.yml`.

## Why a Customer Would Want This
Maintainers evaluating scheduled detectors often want the fully autonomous detector-to-fixer path, but the generated workflow pages currently embed only the default example. When a workflow already ships a chained example, users should be able to copy it directly from the docs page without jumping back to the repository tree or piecing the pattern together from separate chaining docs.

## Rough Implementation Sketch
- Extend `docs/hooks.py` to discover optional example variants next to `example.yml` (starting with `example-chained.yml`).
- Render additional sections such as `## Chained Example Workflow` after the existing `## Example Workflow` block.
- Add a focused `tests/test_docs_hooks.py` case that creates a temporary workflow directory with both `example.yml` and `example-chained.yml` and asserts both snippets are present.
- Keep the first iteration narrow to already-existing files; no new workflow templates are required.

## Why It Won't Be That Hard
The docs generator already centralizes workflow page creation in one helper: `docs/hooks.py` reads `README.md` and `example.yml` in `_generate_page` and appends a single YAML block. Adding optional sibling example rendering is a small extension to that helper plus one existing test module.

## Evidence
- `docs/hooks.py:81-84` reads only `README.md` and `example.yml` for each generated workflow page.
- `docs/hooks.py:114` appends a single `## Example Workflow` YAML block.
- Existing tests already cover `_generate_page` behavior in `tests/test_docs_hooks.py:22-60`, so there is a natural place for coverage.
- The repository already ships chained examples for five detector workflows: `gh-agent-workflows/bug-hunter/example-chained.yml`, `gh-agent-workflows/code-complexity-detector/example-chained.yml`, `gh-agent-workflows/code-duplication-detector/example-chained.yml`, `gh-agent-workflows/newbie-contributor-patrol/example-chained.yml`, and `gh-agent-workflows/test-coverage-detector/example-chained.yml`.
- `docs/workflows/gh-agent-workflows/bugs.md:19-27` already advertises a chained install path, but the generator still only embeds `example.yml` on generated pages.

Duplicate check: this is distinct from #1441 (new comment-only chained templates), #887 (permissions in chaining quick-start), #1201 (homepage Bug Hunter setup path), and #849 (Text Auditor chained setup visibility). This proposal is the small reusable docs-generator feature that surfaces alternate examples that already exist.

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[What is this?](https://ela.st/github-ai-tools) | [From workflow: Trigger Product Manager Impersonator](https://github.com/elastic/ai-github-actions/actions/runs/28439402846)

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Start in docs/hooks.py, especially _generate_page and the lines that read README.md and example.yml and append the example section. Review the existing _generate_page coverage in tests/test_docs_hooks.py, then run that test while checking a temporary workflow containing example.yml and example-chained.yml. Done means both workflow snippets and their sections appear on the generated page.

Written by the indexing model from the issue text.