docs: promote How to Use heading to h2 for consistency with Claude assistant page (#1253)

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

Author: arcappcircle

docs/appcircle-ai/ai-assistants/appcircle-gpt-assistant.md

@@ -10,7 +10,7 @@ import Screenshot from '@site/src/components/Screenshot';
 Appcircle provides a custom [**Appcircle GPT Assistant**](https://chatgpt.com/g/g-686e31aa891481919ef3603325b15ae0-appcircle-assistant) designed to deliver quick and clear answers, offering step-by-step guidance and troubleshooting support for users.
 
 
-### How to Use Appcircle GPT Assistant
+## How to Use Appcircle GPT Assistant
 
 Getting started with the Appcircle GPT Assistant is simple. Just follow these steps: