docs: Fixed Incorrect Model Name in API Integration

Author: mdqst

docs/README.md

@@ -67,7 +67,7 @@ You can run Grok models by setting the `XAI_MODEL` environment variable to `grok
 
 ### Run with OpenAI
 
-You can run OpenAI models by setting the `XAI_MODEL` environment variable to `gpt-4o-mini` or `gpt-4o`
+You can run OpenAI models by setting the `XAI_MODEL` environment variable to `gpt-4-mini` or `gpt-4o`
 
 ## Additional Requirements