Merge pull request #45 from 0xPlaygrounds/fix/docs

fix(docs): Docs still referring to old types

rig-core/src/lib.rs

@@ -22,7 +22,7 @@
 //!     // This requires the `OPENAI_API_KEY` environment variable to be set.
 //!     let openai_client = openai::Client::from_env();
 //!
-//!     let gpt4 = openai_client.model("gpt-4").build();
+//!     let gpt4 = openai_client.agent("gpt-4").build();
 //!
 //!     // Prompt the model and print its response
 //!     let response = gpt4