[Observability Docs] add user-specific prompts docs (#1705)

This PR closes [Issue
4815](https://github.com/elastic/observability-docs/issues/4815) and
adds instructions on adding user-specific prompts that apply to all
subsequent responses.

---------

Co-authored-by: Brandon Morelli <[email protected]>
Co-authored-by: Søren Louv-Jansen <[email protected]>
Co-authored-by: florent-leborgne <[email protected]>

Author: 4 people

solutions/observability/observability-ai-assistant.md

@@ -192,6 +192,30 @@ After creating the pipeline, complete the following steps:
 
     Ask something to the AI Assistant related with the indexed data.
 
+### Add user-specific system prompts
+
+User-specific prompts customize how the AI assistant responds by appending personalized instructions to built-in system prompts. For example, you could specify "Always respond in French," and all subsequent responses will be in French.
+
+A user-specific prompt only applies to the user that sets it.
+
+To edit the **User-specific System Prompt**:
+
+1. Go to the **{{obs-ai-assistant}}** management page. You can find it in the **Management** menu or by using the [global search field](/explore-analyze/find-and-organize/find-apps-and-objects.md).
+3. Switch to the **Knowledge base** tab.
+4. Select **Edit User-specific Prompt**.
+
+#### User-specific prompt example
+User-specific prompts are useful when configuring specific workflows. For example, if you want the assistant to respond in a consistent, readable format when asked about Kubernetes metadata, you might add the following **user-specific system prompt**:
+
+```
+<kubernetes_info>
+If asked about a Kubernetes pod, namespace, cluster, location, or owner, return the info in this format.  Use the field names to find the relevant information requested.  Don't mention the field names, just the results.
+- Pod: agent.name
+- Namespace: data_stream.namespace
+- Cluster Name: orchestrator.cluster.name
+- Owner: cloud.account.id
+</kubernetes_info>
+```
 
 ## Interact with the AI Assistant [obs-ai-interact]