Security AI Assistant access to Elastic Docs in air-gapped envs (#2598)

Fixes #2404 by documenting the process for enabling AI Assistant to
access Elastic documentation from an air-gapped environment. The process
is a bit different from that for the Obs/Search Assistant, since the
Assistants' settings UIs are different, so I confirmed the process for
the Security AI Assistant directly with someone who works on it.

---------

Co-authored-by: natasha-moore-elastic <[email protected]>

Author: benironside

solutions/security/ai/ai-assistant-knowledge-base.md

@@ -38,6 +38,11 @@ The `Elastic AI Assistant: All` role privilege allows you to use AI Assistant an
 :alt: Knowledge base's RBAC settings
 :::
 
+## Give AI Assistant access to Elastic's product documentation [elastic-docs]
+
+When you enable Knowledge Base, AI Assistant automatically gains access to Elastic's product documentation. This improves its answers to questions related to Elastic products and features.
+
+In air-gapped environments, this requires additional configuration. Refer to the [{{kib}} AI Assistant settings documentation](kibana://reference/configuration-reference/ai-assistant-settings.md) for detailed instructions. Once you complete the instructions on that page, AI Assistant will automatically gain access to Elastic's documentation as soon as you start a new conversation.
 
 ## Enable Knowledge Base [enable-knowledge-base]
 

solutions/security/ai/ai-assistant.md

@@ -122,7 +122,7 @@ To adjust AI Assistant's settings from the chat window, click the **More** (thre
 :screenshot:
 ::::
 
-The first three options (**AI Assistant settings**, **Knowledge Base**, and **Anonymization**) open the corresponding tabs of the **Security AI settings** page. The **Chat options** affect display-only user settings: whether to show or hide anonymized values, and whether to include citations. When citations are enabled, AI Assistant will refer you to information sources including data you've shared with it, information you've added to the knowledge base, and content from Elastic's Security Labs and product documentation.
+The first three options (**AI Assistant settings**, **Knowledge Base**, and **Anonymization**) open the corresponding tabs of the **Security AI settings** page. The **Chat options** affect display-only user settings: whether to show or hide anonymized values, and whether to include citations. When citations are enabled, AI Assistant will refer you to information sources including data you've shared with it, information you've added to the [knowledge base](/solutions/security/ai/ai-assistant-knowledge-base.md), and content from Elastic's Security Labs and [product documentation](/solutions/security/ai/ai-assistant-knowledge-base.md#elastic-docs).
 
 The **Security AI settings** page provides a range of configuration options for AI Assistant. To access it directly, use the global search field to search for "AI Assistant for Security".