readme: update main instance api url

README.md

@@ -55,7 +55,7 @@ this list is not final and keeps expanding over time. if support for a service y
 ## cobalt api
 cobalt has an open api that you can use in your projects *for free~*. it's easy and straightforward to use, [check out the docs](/docs/api.md) to learn how to use it. 
 
-✅ you can use the main api instance ([co.wuk.sh](https://co.wuk.sh/)) in your **personal** projects.  
+✅ you can use the main api instance ([api.cobalt.tools](https://api.cobalt.tools/)) in your **personal** projects.  
 ❌ you cannot use the free api commercially (anywhere that's gated behind paywalls or ads). host your own instance for this.
 
 we reserve the right to restrict abusive/excessive access to the main instance api.