Update README.md

Author: Raiou

README.md

@@ -35,6 +35,8 @@ sudo systemctl reload httpd
 
 All set! UpCloud can now be found as an infrastructure provider on your WHMCS admin panel. But before you can begin setting up cloud plans, you'll need to configure API access to your UpCloud account if you haven't already done so.
 
+Follow the instructions at our [API tutorial](https://upcloud.com/community/tutorials/getting-started-upcloud-api/) to configure new API credentials for WHMCS.
+
 ## Usage
 
 You should have a working installation of WHMCS together with the UpCloud module to start configuring your services.