Update README.md

Implementation of codex engine

Author: Godzab

README.md

@@ -41,9 +41,9 @@ response, err := cl.Call(&req)
 
 ## Support
 - List Engines API
-- Completion API
+- Completion API (CODEX Engines Support Available)
 - Document Search API
 - Files List API
 - Answers API
 - Classification API
-- Enhanced Search API
+- Enhanced Search API