docs: add link to class-validator-extended

fixes #2003

README.md

@@ -928,12 +928,13 @@ usages.
 
 ## Extensions
 
-There are several extensions that simplify class-validator integration with other modules:
+There are several extensions that simplify class-validator integration with other modules or add additional validations:
 
 - [class-validator integration](https://github.com/19majkel94/class-transformer-validator) with [class-transformer](https://github.com/pleerock/class-transformer)
 - [class-validator-rule](https://github.com/yantrab/class-validator-rule)
 - [ngx-dynamic-form-builder](https://github.com/EndyKaufman/ngx-dynamic-form-builder)
 - [abarghoud/ngx-reactive-form-class-validator](https://github.com/abarghoud/ngx-reactive-form-class-validator)
+- [class-validator-extended](https://github.com/pigulla/class-validator-extended)
 
 ## Release notes