suggest the virtual package

Author: Nyholm

composer.json

@@ -41,7 +41,7 @@
         "php-http/cookie": "Allow to use CookiePlugin",
         "symfony/stopwatch": "Allow to use the StopwatchPlugin",
         "psr/log-implementation": "Allow to use the LoggerPlugin",
-        "psr/cache": "Allow to use the CachePlugin",
+        "psr/cache-implementation": "Allow to use the CachePlugin",
         "php-http/encoding": "Allow to use the Decoder and Encoder plugin"
     },
     "scripts": {