Adds EASE to feature tiers doc (#2468)

Fixes
[elastic/docs-content-internal/issues/171](elastic/docs-content-internal#171).
Adds the new feature tier's description, and adjusts the other
descriptions accordingly.

Preview:
[here](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/2468/deploy-manage/deploy/elastic-cloud/project-settings#elastic-sec-project-features)

Author: benironside

deploy-manage/deploy/elastic-cloud/project-settings.md

@@ -63,11 +63,16 @@ For {{elastic-sec}} projects, edit the **Project features** to select a feature
 
 | Feature tier | Description and add-ons |
 | :--- | :--- |
-| **Security Analytics Essentials** | Standard security analytics, detections, investigations, and collaborations. Allows these add-ons:<br><br>* **Endpoint Protection Essentials**: endpoint protections with {{elastic-defend}}.<br>* **Cloud Protection Essentials**: Cloud native security features.<br> |
+| **Elastic AI SOC Engine (EASE)** | A package of AI-powered tools meant to work with and enhance your existing SOC platforms: triage and correlate alerts from any platform using Attack Discovery, get realtime recommendations and assistance from AI Assistant, and share insights with your other tools.  |
+| **Security Analytics Essentials** | Everything in EASE, plus a suite of security analytics, detections, investigations, and collaboration tools. Allows these add-ons:<br><br>* **Endpoint Protection Essentials**: endpoint protections with {{elastic-defend}}.<br>* **Cloud Protection Essentials**: Cloud native security features.<br> |
 | **Security Analytics Complete** | Everything in **Security Analytics Essentials** plus advanced features such as entity analytics, threat intelligence, and more. Allows these add-ons:<br><br>* **Endpoint Protection Complete**: Everything in **Endpoint Protection Essentials** plus advanced endpoint detection and response features.<br>* **Cloud Protection Complete**: Everything in **Cloud Protection Essentials** plus advanced cloud security features.<br> |
 
 #### Downgrading the feature tier [elasticsearch-manage-project-downgrading-the-feature-tier]
 
+:::{note}
+You cannot downgrade to EASE from any other feature tier. You can upgrade from EASE to other tiers.
+:::
+
 When you downgrade your Security project features selection from **Security Analytics Complete** to **Security Analytics Essentials**, the following features become unavailable:
 
 * All Entity Analytics features