Merge pull request #20 from PHPCSStandards/feature/readme-update-composer-2.2

README: update for Composer 2.2

Author: jrfnl

README.md

@@ -32,13 +32,15 @@ Installation
 
 Run the following from the root of your project:
 ```bash
+composer config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true
 composer require --dev phpcsstandards/phpcsdevcs:"^1.0"
 ```
 
 ### Composer Global Installation
 
 If you work on several different sniff repos, you may want to install this toolset globally:
 ```bash
+composer global config allow-plugins.dealerdirect/phpcodesniffer-composer-installer true
 composer global require --dev phpcsstandards/phpcsdevcs:"^1.0"
 ```