## Summary

[Support collapsible section in Integration
README](https://github.com/elastic/integration-experience/issues/82)
The public Integrations docs page recently added support for collapsible
sections (e.g., for field tables and sample events). This PR brings the
same functionality to Kibana to reduce scrolling and help users focus on
the most relevant information.

To display an accordion, the README should include the following markup:
```
<details>
  <summary>Click to expand</summary>
  This content is hidden by default.
</details>
```
However, we do not want to modify the integration READMEs directly.
Doing so would cause these tags to appear as raw HTML in older versions
of Kibana
Bumping the minimum supported Kibana version for each integration is
also not a solution, as it would complicate backports and maintenance.

#### Proposed solution
Detect in Kibana parts that should be collapsible, like `exported
fields` and update the markdown with the necessary markups. Similar to
what the `integration-docs` does in
https://github.com/elastic/integration-docs/issues/342


#### Dependencies added:
- `rehype-raw`: Parse and render HTML inside Markdown.
- `rehype-sanitize`: Sanitize potentially unsafe HTML.

#### Version pinning for compatibility
- `rehype-sanitize@4.0.0`: Uses hast-util-sanitize@3+, which provides a
built-in default schema and is compatible with CommonJS environments.
- `rehype-raw@5.1.0`: The latest version that supports CommonJS. Later
versions are ESM-only.



https://github.com/user-attachments/assets/15f0822b-9b36-45e6-a47e-c8fa0dedd4c3



### Checklist

Check the PR satisfies following conditions. 

Reviewers should verify this PR satisfies this list as well.

- [ ] Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/src/platform/packages/shared/kbn-i18n/README.md)
- [ ]
[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios
- [ ] If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)
- [ ] This was checked for breaking HTTP API changes, and any breaking
changes have been approved by the breaking-change committee. The
`release_note:breaking` label should be applied in these situations.
- [ ] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed
- [ ] The PR description includes the appropriate Release Notes section,
and the correct `release_note:*` label is applied per the
[guidelines](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process

)

### Identify risks

Does this PR introduce any risks? For example, consider risks like hard
to test bugs, performance regression, potential of data loss.

Describe the risk, its severity, and mitigation for each identified
risk. Invite stakeholders and evaluate how to proceed before merging.

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>