added the feature on readme

Author: devwithkunal

README.md

@@ -5,6 +5,7 @@ It's a standalone single file PHP class to use on your projects. It requires no
 
 ## What's New
 - **Date validation** - Validate date format and date range
+- **Field alias** - Set alias on field names for error messages
 
 ## How To Use
 You only need only one file: