Moved symfony/config from the "recommend" dependency to the "suggest" dependency. Cannot find "recommend" in composer documentation

src/Symfony/Component/DependencyInjection/composer.json

@@ -18,10 +18,8 @@
     "require": {
         "php": ">=5.3.2"
     },
-    "recommend": {
-        "symfony/config": "self.version"
-    },
     "suggest": {
+        "symfony/config": "self.version"
         "symfony/yaml": "self.version"
     },
     "autoload": {