[ci skip] DocBlocks for DB drivers' result classes

Partially fixes issue #1295.
diff --git a/system/database/drivers/sqlsrv/sqlsrv_result.php b/system/database/drivers/sqlsrv/sqlsrv_result.php
index fc66d9d..6d24cc9 100644
--- a/system/database/drivers/sqlsrv/sqlsrv_result.php
+++ b/system/database/drivers/sqlsrv/sqlsrv_result.php
@@ -146,7 +146,7 @@
 	 *
 	 * Returns the result set as an object
 	 *
-	 * @param	string
+	 * @param	string	$class_name
 	 * @return	object
 	 */
 	protected function _fetch_object($class_name = 'stdClass')