update README

Author: xiongcc

README.md

@@ -26,4 +26,4 @@ This project has been started by [@NikolayS]() on 2023-09-26 https://twitter.com
 - 0003 [How to troubleshoot long Postgres startup](https://github.com/xiongcccc/postgres-howto/blob/master/How%20to%20troubleshoot%20long%20Postgres%20startup.md)
 - 0004 [Understanding how sparsely tuples are stored in a table](https://github.com/xiongcccc/postgres-howto/blob/master/Understanding%20how%20sparsely%20tuples%20are%20stored%20in%20a%20table.md)
 - 0005 [How to work with pg_stat_statments, part 1](https://github.com/xiongcccc/postgres-howto/blob/master/How%20to%20work%20with%20pg_stat_statements%2C%20part%201.md)
-
+- 0006 [How to work with pg_stat_statments, part 2](https://github.com/xiongcccc/postgres-howto/blob/master/How%20to%20work%20with%20pg_stat_statements%2C%20part%202.md)