[DOC] Add documentation for AD contextual launch

[jackiehanyang]

What do you want to do?

• Request a change to existing documentation
• Add new documentation
• Report a technical problem with the documentation
• Other

Tell us about your request. Provide a summary of the request.
Request AD documentation on this contextual launch feature

Version: List the OpenSearch version to which this issue applies, e.g. 2.14, 2.12--2.14, or all.
3.0-beta and above

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.
PR - opensearch-project/anomaly-detection-dashboards-plugin#1005
Issue - opensearch-project/anomaly-detection-dashboards-plugin#875