Composer: suggest composer plugin & update README

Fixes the open actions for PR 855.

README.md

@@ -47,7 +47,7 @@ The WordPress Coding Standards are currently [not compatible with the upcoming P
 
 ### Composer
 
-Standards can be installed with [Composer](https://getcomposer.org/) dependency manager:
+Standards can be installed with the [Composer](https://getcomposer.org/) dependency manager:
 
     composer create-project wp-coding-standards/wpcs --no-dev
 
@@ -60,6 +60,16 @@ Running this command will:
 
 For convenience of using `phpcs` as global command you might want to add path to `wpcs/vendor/bin` directory to a `PATH` environment of your operating system.
 
+#### Installing WPCS as a dependency
+
+When installing the WordPress Coding Standards as a dependency in a larger project, the above mentioned step 3 will not be executed automatically.
+
+There are two actively maintained Composer plugins which can handle the registration of standards with PHP_CodeSniffer for you:
+* [composer-phpcodesniffer-standards-plugin](https://github.com/higidi/composer-phpcodesniffer-standards-plugin)
+* [phpcodesniffer-composer-installer](https://github.com/DealerDirect/phpcodesniffer-composer-installer)
+
+It is strongly suggested to `require` one of these plugins in your project to handle the registration of external standards with PHPCS for you.
+
 ### Standalone
 
 1. Install PHP_CodeSniffer by following its [installation instructions](https://github.com/squizlabs/PHP_CodeSniffer#installation) (via Composer, PEAR, or Git checkout).

composer.json

@@ -13,6 +13,9 @@
 	"require"    : {
 		"squizlabs/php_codesniffer": "^2.9.0"
 	},
+	"suggest" : {
+		"dealerdirect/phpcodesniffer-composer-installer": "*"
+	},
 	"minimum-stability" : "RC",
 	"support"    : {
 		"issues": "https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards/issues",