[DOC] Add demo section to README with improved GIF

* Add a new "Demo" section to the README
* Include an updated demo GIF showcasing CommitAi in action
  - The new GIF demonstrates generating a commit without additional input
  - It specifically highlights the usage of Claude 3 Opus for commit generation

The demo section provides a visual representation of CommitAi's functionality, giving potential users a quick overview of how the tool simplifies the commit message creation process using AI technologies.

README.md

@@ -8,8 +8,12 @@
 
 **CommitAi** simplifies the Git commit message creation process by leveraging AI technologies, including GPT-4 and Claude. Designed for developers who value clarity and precision in commit histories, **CommitAi** offers a streamlined workflow that transforms your staged changes and high-level explanations into informative commit messages. Enhance your project documentation and streamline your development process with commit messages that truly reflect your changes.
 
+## Demo
+
 ![CommitAi Demo](./assets/commitaai.gif)
 
+This demo GIF shows CommitAi in action, demonstrating how it generates a commit without any additional input, using Claude 3 Opus.
+
 ## Features
 
 - **Intelligent Commit Generation**: Leverages state-of-the-art AI models to generate meaningful commit messages from your changes.