docs: clarify package purpose in composer.json description

composer.json

 {
     "name": "quiqqer/test",
     "type": "quiqqer-plugin",
-    "description": "Its an installation test. This package do nothing. TEST STRING 6000 ew089f 0203 2003232 4",
+    "description": "This is a testing package. Install at your own risk.",
     "license": "MIT",
     "authors": [
         {