fixes note bug

docs/AI-for-security/knowledge-base.asciidoc

@@ -157,6 +157,7 @@ First, you'll need to set up a web crawler to add the desired data to an index,
 . The previous step opens a page with the details of your new index. Go to its **Mappings** tab, then click **Add field**. 
 + 
 NOTE: Remember, each index added to Knowledge Base must have at least one semantic text field.
++
 .. Under **Field type**, select `Semantic text`. Under **Select an inference endpoint**, select `elastic-security-ai-assistant-elser2`. Click **Add field**, then **Save mapping**.
 . Go to the **Scheduling** tab. Enable the **Enable recurring crawls with the following schedule** setting, and define your desired schedule.
 . Go to the **Manage Domains** tab. Select the domain associated with your new web crawler, then go the its **Crawl rules** tab and click **Add crawl rule**. For more information, refer to {enterprise-search-ref}/crawler-extraction-rules.html[Web crawler content extraction rules].