docs: add doc for phpclass snippet

Author: aspirantzhang

README.md

@@ -2,12 +2,20 @@
 
 [![VScode](https://img.shields.io/badge/Extension-VScode-blueviolet.svg)](https://marketplace.visualstudio.com/items?itemName=aspirantzhang.php-enhanced-snippets)
 ![PHP8](https://img.shields.io/badge/PHP-%5E8.0-blue.svg)
+[![PSR-2](https://img.shields.io/badge/Standard-PSR--2-%2326A69A.svg)](https://www.php-fig.org/psr/psr-2/)
 [![PSR-12](https://img.shields.io/badge/Standard-PSR--12-%2326A69A.svg)](https://www.php-fig.org/psr/psr-12/)
 
 **This [VScode extension](https://marketplace.visualstudio.com/items?itemName=aspirantzhang.php-enhanced-snippets) provide a complete set of code snippets for PHP developers.**
 
 You can use it to avoid wasting time typing Class blocks, function signatures or other common PHP statements.
 
+## Snippets
+
+### Class related
+| Snippet | Output |
+| --- | --- |
+| phpclass | `standard php class` |
+
 ## Special Thanks
 This extension is forked from [h4kst3r/php-awesome-snippets](https://github.com/h4kst3r/php-awesome-snippets). Because its author seems to have not maintained it for a long time. So I made this fork to make the extension suitable for new version of PHP. I re-planned the shortcut keys, and add more standardized writing methods. Great thanks to h4kst3r's excellent work.