chore: docs (#48)

Author: bukinoshita

readme.md

@@ -2,6 +2,14 @@
 
 This example shows how to use Resend with [Remix](https://remix.run).
 
+## Prerequisites
+
+To get the most out of this guide, you’ll need to:
+
+- [Create an API key](https://resend.com/api-keys)
+- [Verify your domain](https://resend.com/domains)
+
+
 ## Instructions
 
 1. Define environment variables in `.env` file.