Merge pull request #8781 from owncloud/add-a-warning-to-the-sample

Add a warning to the configuration file

config/config.sample.php

 <?php
 
+/**
+ * This configuration file is only provided to document the different configuration options and their usage.
+ * DO NOT COMPLETELY BASE YOUR CONFIGURATION FILE ON THIS SAMPLE. THIS MAY BREAK YOUR INSTANCE.
+ * Instead, manually copy configurations' switches that you consider important for your instance to your configuration.
+ */
+
 /* Only enable this for local development and not in productive environments */
 /* This will disable the minifier and outputs some additional debug informations */
 define("DEBUG", true);