Add Agile Manifesto

Author: brahinets

Diff for: sites.md

@@ -7,3 +7,4 @@
 | **Next step** | _Become a database Jedi_ | `db` `database` `relational database` `sql`                   | [Use the index Luke](https://use-the-index-luke.com)      |
 | **Next step** |  _Keep the memories_     | `db` `database` `relational database` `sql` `postgres`        | [PostgreSQL Tutorial](https://www.postgresqltutorial.com) |
 | **Next step** | _Be a better manager_    | `management` `engineering` `people` `technology` `leadership` | [TechTello](https://www.techtello.com/)                   |
+| **Next step** | _Adapt, collaborate, deliver fast!_    | `team work` `management` `engineering` `people` `technology` | [Agile Manifesto](https://agilemanifesto.org/)                   |