[Workflows 9.3] Document Workflows in Security docs

[natasha-moore-elastic]

Summary

Resolves https://github.com/elastic/docs-content-internal/issues/747 and #5041 by documenting Workflows in Security docs:

• Documents Workflows as a navigation item in https://www.elastic.co/docs/solutions/security/get-started/elastic-security-ui
• Adds a tip about setting up a workflows rule action in https://www.elastic.co/docs/solutions/security/detect-and-alert/create-detection-rule#rule-notifications

@tinnytintin10 / @jamesspi please let me know if there is anywhere else in the Security UI that Workflows are available from in 9.3.

Generative AI disclosure

1. Did you use a generative AI (GenAI) tool to assist in creating this contribution?

• Yes
• No

[github-actions]

✅ Vale Linting Results

No issues found on modified lines!

---

The Vale linter checks documentation changes against the Elastic Docs style guide.

To use Vale locally or report issues, refer to Elastic style guide for Vale.

[github-actions]

🔍 Preview links for changed docs

• solutions/security/detect-and-alert/create-detection-rule.md
• solutions/security/get-started/elastic-security-ui.md