[Streams] Document query stream value proposition vs raw ES|QL views

## 📓 Summary

Users can create ES|QL views directly in Discover or use query streams within the Streams app, but the differences between these approaches and when to use each are unclear. Without clear guidance, users may be confused about whether to create a query stream or just work with ES|QL views in Discover.

Query streams provide additional capabilities beyond raw ES|QL views (e.g., significant events, attached assets, hierarchical organization), but these benefits need to be clearly articulated.

## ✔️ Acceptance criteria

* Documentation clearly explains the differences between query streams and raw ES|QL views
* Guidelines help users decide when to create a query stream vs working with views in Discover
* The unique benefits of query streams are highlighted (significant events, asset attachment, stream hierarchy, governance, metadata)
* Examples illustrate common scenarios and which approach to use
* In-product messaging or tooltips guide users toward query streams when appropriate
* Training materials and demos showcase query stream advantages

## 💡 Implementation hints

* Key differentiators to document:
* **Query Streams:** Persistent, governed, support significant events, allow asset attachment (dashboards/alerts/SLOs), appear in stream hierarchy, have metadata and ownership
* **Raw ES|QL Views:** Ad-hoc exploration, temporary, no governance or asset management, useful for one-off analysis

* Create a decision flowchart:
* "Do you need to attach dashboards or alerts?" → Query Stream
* "Do you need significant events discovery?" → Query Stream
* "Just exploring data temporarily?" → Raw ES|QL view in Discover
* "Need to organize and govern this data subset?" → Query Stream

* Add contextual help in Discover, suggesting when to "Save as Query Stream"
* Include comparison table in documentation showing feature availability

FYI @mdbirnstiehl