Replace mentions of phpcs and phpcbf with composer scripts

Author: Koopzington

CONTRIBUTING.md

@@ -84,14 +84,14 @@ standards checks, and provides configuration for our selected checks.
 To run checks only:
 
 ```console
-$ ./vendor/bin/phpcs
+$ composer cs-check
 ```
 
 `phpcs` also includes a tool for fixing most CS violations, `phpcbf`:
 
 
 ```console
-$ ./vendor/bin/phpcbf
+$ composer cs-fix
 ```
 
 If you allow `phpcbf` to fix CS issues, please re-run the tests to ensure