Update README subtitle to use h2 heading for better visibility

Author: robertpiosik

README.md

@@ -7,7 +7,7 @@
     </picture>
   </a>
 </p>
-<p align="center">Fast AI coding with chatbots/APIs</p>
+<h2 align="center">Fast AI coding with chatbots/APIs</h2>
 <p align="center">
   <a href="https://marketplace.visualstudio.com/items?itemName=robertpiosik.gemini-coder" target="_blank"><img src="https://img.shields.io/badge/Install-VS_Code_Marketplace-blue" alt="Get from Visual Studio Code Marketplace" /></a> <a href="https://open-vsx.org/extension/robertpiosik/gemini-coder" target="_blank"><img src="https://img.shields.io/badge/Install-Open_VSX_Registry-a60ee5" alt="Get from Open VSX Registry" /></a> <a href="https://github.com/robertpiosik/CodeWebChat/blob/dev/LICENSE" target="_blank"><img src="https://img.shields.io/badge/License-GPL--3.0-green.svg" alt="GPL-3.0 license" /></a>
 </p>