Remove unwanted colon in code samples

When setParameter{s,} is called, we know we are dealing with parameters.
It makes sense that this colon is unneeded, and since it results in an
error being thrown, let us document the one true way of using that API
instead.

src/Query/QueryBuilder.php

@@ -405,7 +405,7 @@ public function getSQL()
      *         ->select('u')
      *         ->from('users', 'u')
      *         ->where('u.id = :user_id')
-     *         ->setParameter(':user_id', 1);
+     *         ->setParameter('user_id', 1);
      * </code>
      *
      * @param int|string           $key   Parameter position or name
@@ -434,8 +434,8 @@ public function setParameter($key, $value, $type = null)
      *         ->from('users', 'u')
      *         ->where('u.id = :user_id1 OR u.id = :user_id2')
      *         ->setParameters(array(
-     *             ':user_id1' => 1,
-     *             ':user_id2' => 2
+     *             'user_id1' => 1,
+     *             'user_id2' => 2
      *         ));
      * </code>
      *