remove PHP codesniffer from readme

Author: gregor-j

README.md

@@ -5,12 +5,5 @@
 
 This repository defines interfaces for implementing the [PHP/SAP][phpsap] API.
 
-## Coding standards
-
-This project uses [PSR-12] coding standard and [PHP_CodeSniffer] for validations.
-In order to validate before a commit, call `vendor/bin/phpcs`.
-
 [phpsap]: https://php-sap.github.io
 [license-mit]: https://img.shields.io/badge/license-MIT-blue.svg
-[PSR-12]: https://www.php-fig.org/psr/psr-12/
-[PHP_CodeSniffer]: https://github.com/squizlabs/PHP_CodeSniffer