Update README.md

Signed-off-by: Jenna Winkler <135358348+jenna-winkler@users.noreply.github.com>

Author: jenna-winkler

README.md

@@ -85,7 +85,7 @@ agentstack run example_agent "Alice"  # Test your agent
 You should see: "Ciao Alice!" 🎉
 
 > [!TIP]
-> Check out [Start Building Agents](https://agentstack.beeai.dev/introduction/start-building-agents) for a complete step-by-step guide to creating your first agent.
+> Check out [Building Agents](https://agentstack.beeai.dev/guides/building-agents) for a complete step-by-step guide to creating your first agent.
 
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