Update README.md

I noticed the link for 04-end was wrong when I was following along

Author: hyrmn

README.md

@@ -11,7 +11,7 @@ Learn how to use serverless functions in less than 30 minutes!
 | [Introduction with Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/introduction-with-serverless-functions)                                         | -                                                                                                         | -                                                                                                       |
 | [Project Setup with Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/project-setup-with-serverless-functions)                                       | [Start Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/02-begin) | [End Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/02-end)   |
 | [Create Your First Serverless Function](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/create-your-first-serverless-function)                                           | [Start Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/03-begin) | [End Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/03-end)   |
-| [Integrate with a Third Party API with Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/integrate-with-a-third-party-api-with-serverless-functions) | [Start Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/04-begin) | [End Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/04-begin) |
+| [Integrate with a Third Party API with Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/integrate-with-a-third-party-api-with-serverless-functions) | [Start Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/04-begin) | [End Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/04-end) |
 | [Deploying Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/deploying-serverless-functions)                                                         | -                                                                                                         | -                                                                                                       |
 | [Customizing the Request with Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/customizing-the-request-with-serverless-functions)                   | [Start Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/06-begin) | [End Code](https://github.com/netlify/explorers-up-and-running-with-serverless-functions/tree/06-end)   |
 | [The Power of Atomic Serverless Functions](https://explorers.netlify.com/learn/up-and-running-with-serverless-functions/the-power-of-atomic-serverless-functions)                                     | -                                                                                                         | -                                                                                                       |