[phpdoc] Add API documentation.

This is a starting point to add a documentation of the whole set of APIs and
classes of Predis. The next step will be to actually improve and extend it.

lib/Predis/Protocol/Text/ResponseErrorHandler.php

@@ -15,8 +15,21 @@ use Predis\ServerException;
 use Predis\Protocol\IResponseHandler;
 use Predis\Network\IConnectionComposable;
 
+/**
+ * Implements a response handler for error replies using the standard wire
+ * protocol defined by Redis.
+ *
+ * This handler throws an exception to notify the user that an error has
+ * occurred on the server.
+ *
+ * @link http://redis.io/topics/protocol
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
 class ResponseErrorHandler implements IResponseHandler
 {
+    /**
+     * {@inheritdoc}
+     */
     public function handle(IConnectionComposable $connection, $errorMessage)
     {
         throw new ServerException($errorMessage);