[Security] [July 22] Replace default quick prompts with prompt tiles (#1985)

Contributes to #1932.

Documents the new prompt tiles in the AI Assistant "new chat" UI and the
removal of the default quick prompts.

Preview: [Interact with AI
Assistant](https://docs-v3-preview.elastic.dev/elastic/docs-content/pull/1985/solutions/security/ai/ai-assistant#interact-with-assistant)

Author: natasha-moore-elastic

solutions/images/security-assistant-basic-view.png

@@ -17,6 +17,7 @@ The Elastic AI Assistant utilizes generative AI to bolster your cybersecurity op
 
 :::{image} /solutions/images/security-assistant-basic-view.png
 :alt: Image of AI Assistant chat window
+:width: 75%
 :screenshot:
 :::
 
@@ -81,23 +82,24 @@ Each user’s chat history (up to the 99 most recent conversations) and custom Q
 
 ## Interact with AI Assistant [interact-with-assistant]
 
-Use these features to adjust and act on your conversations with AI Assistant:
+Use these optional features to adjust and act on your conversations with AI Assistant:
 
-* (Optional) Select a *System Prompt* at the beginning of a conversation by using the **Select Prompt** menu. System Prompts provide context to the model, informing its response. To create a System Prompt, open the System Prompts dropdown menu and click **+ Add new System Prompt…**.
-* (Optional) Select a *Quick Prompt* at the bottom of the chat window to get help writing a prompt for a specific purpose, such as summarizing an alert or converting a query from a legacy SIEM to {{elastic-sec}}.
+* Select a *System Prompt* at the beginning of a conversation by using the **Select Prompt** menu. System Prompts provide context to the model, informing its response. To create a System Prompt, open the System Prompts dropdown menu and click **+ Add new System Prompt…**.
+* {applies_to}`stack: ga 9.1` Select a *prompt tile* to start your conversation with a predefined goal or topic. Prompt tiles help you begin structured tasks or investigations into common {{elastic-sec}} workflows. The available prompt tiles include:
 
-   :::{image} /solutions/images/security-quick-prompts.png
-   :alt: Quick Prompts highlighted below a conversation
-   :screenshot:
-   :::
+   * **Alerts**: Quickly identify and prioritize the most important alerts from the last 24 hours.
+   * **Research**: Get a summary of the latest {{elastic-sec}} Labs research articles.
+   * **Query**: Generate {{esql}} queries based on a specific goal or requirement.
+   * **Suggest**: Explore the types of questions you can ask AI Assistant about {{elastic-sec}}.
 
-* System Prompts and Quick Prompts can also be configured from the corresponding tabs on the **Security AI settings** page.
+* {applies_to}`stack: removed 9.1` Select a default *Quick Prompt* at the bottom of the chat window to get help writing a prompt for a specific purpose, such as summarizing an alert or converting a query from a legacy SIEM to {{elastic-sec}}. The default Quick Prompts' availability varies based on context—for example, the **Alert summarization** Quick Prompt appears when you open AI Assistant while viewing an alert.
 
-   :::{image} /solutions/images/security-assistant-settings-system-prompts.png
-   :alt: The Security AI settings menu's System Prompts tab
-   :::
+* Create new custom Quick Prompts by clicking **Add quick prompt**.
+
+:::{tip}
+System Prompts and Quick Prompts can also be [configured](#configure-ai-assistant) from the corresponding tabs on the **Security AI settings** page. 
+:::
 
-* Quick Prompt availability varies based on context—for example, the **Alert summarization** Quick Prompt appears when you open AI Assistant while viewing an alert. To customize existing Quick Prompts and create new ones, click **Add Quick Prompt**.
 * In an active conversation, you can use the inline actions that appear on messages to incorporate AI Assistant’s responses into your workflows:
 
     * **Add note to timeline** (![Add note icon](/solutions/images/security-icon-add-note.png "title =20x20")): Add the selected text to your currently active Timeline as a note.