[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/Transaction/AbortedMultiExecException.php

@@ -13,10 +13,20 @@ namespace Predis\Transaction;
 
 use Predis\PredisException;
 
+/**
+ * Exception class that identifies MULTI / EXEC transactions aborted by Redis.
+ *
+ * @author Daniele Alessandri <suppakilla@gmail.com>
+ */
 class AbortedMultiExecException extends PredisException
 {
     private $_transaction;
 
+    /**
+     * @param MultiExecContext $transaction Transaction that generated the exception.
+     * @param string $message Error message.
+     * @param int $code Error code.
+     */
     public function __construct(MultiExecContext $transaction, $message, $code = null)
     {
         parent::__construct($message, $code);
@@ -24,6 +34,11 @@ class AbortedMultiExecException extends PredisException
         $this->_transaction = $transaction;
     }
 
+    /**
+     * Returns the transaction that generated the exception.
+     *
+     * @return MultiExecContext
+     */
     public function getTransaction()
     {
         return $this->_transaction;