[DOCS] Alerts now shown in process tree

[nastasha-solomon]

Description

Alerts are now shown in the process tree whenever an event triggers an alert. Example:

Related issues:

• https://github.com/elastic/security-team/issues/2459

Required doc updates

- Visual event analyzer | Visual event analyzer UI : Might need to refresh screenshots
- Visual event analyzer | Process and event details: Will need to update section title and include screenshots and an explanation for how to view and understand alert details in the event analyzer. Reach out to @michaelolo24 for help understanding the workflows and alert views.

• Create a new topic under the "Technical Preview" section that describes how to enable the flag and shows how to navigate through alert details in event analyzer.

[nastasha-solomon]

Slack convo with product and engineers yielded the following:

• Document the Alerts in Analyzer feature in 8.4 and the feature flag that enables it which is: xpack.securitySolution.enableExperimental: ['insightsRelatedAlertsByProcessAncestry']
• In docs, we should tag the feature as being the technical preview stage. Will also need to place them alongside all of our other Technical Preview docs.