adds section tag

docs/assistant/security-assistant.asciidoc

@@ -166,6 +166,7 @@ When you include a particular event as context, you can use a similar interface
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 The *Show anonymized* toggle controls whether you see the obfuscated or plaintext versions of the fields you sent to AI Assistant. It doesn't control what gets obfuscated — that's determined by the anonymization settings. It also doesn't affect how event fields appear _before_ being sent to AI Assistant. Instead, it controls how fields that were already sent and obfuscated appear to you.
 
+[[ai-assistant-knowledge-base]]
 * **Knowledge base:** Use retrieval-augmented generation to provide additional context to AI Assistant. 
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 beta::[]