chore: fix readme formating [skip ci]

Author: aallam

README.md

@@ -113,10 +113,11 @@ repositories {
 ## ⚠️ Throubleshooting
 
 <details>
-  <summary>I'm seeing "The model: `gpt-4` does not exist"</summary>
+  <summary>I'm seeing "The model: gpt-4 does not exist"</summary>
 
 The access to GPT-4 API is restricted at the moment. You can join the waitlist using [this form](https://openai.com/waitlist/gpt-4-api).
 </details>
+
 ## 📄 License
 
 OpenAI Kotlin API Client is an open-sourced software licensed under the [MIT license](LICENSE.md).