Add admonition explaining baseURL on using-the-agent

Author: adam-cowley

asciidoc/courses/llm-chatbot-typescript/modules/6-agent/lessons/5-using-the-agent/lesson.adoc

@@ -43,6 +43,12 @@ The retrieval tool requires an embedding model.
 include::{repository-raw}/main/{lab-solution}[tag="embeddings", indent=0]
 ----
 
+[IMPORTANT]
+.Defining a `baseURL`
+The `baseURL` configuration option uses the `OPENAI_API_BASE` key to use the GraphAcademy OpenAI Proxy as mentioned in link:../../1-project-setup/2-setup/[the Project Setup lesson^].
+If you are using an OpenAI API key (starting with `sk-`), you can omit the `configuration` options.
+
+
 To interact with the graph, the agent should use link:/courses/llm-chatbot-typescript/3-conversation-history/2-neo4j-graph/[the singleton instance created in the Initializing Neo4j lesson^].
 
 .Embeddings