Update codecov, CI, site map and acknowledgement

Author: Hzxin

README.md

@@ -1,4 +1,5 @@
-[![CI Status](https://github.com/se-edu/addressbook-level3/workflows/Java%20CI/badge.svg)](https://github.com/se-edu/addressbook-level3/actions)
+[![CI Status](https://github.com/AY2021S2-CS2103T-W15-1/tp/workflows/Java%20CI/badge.svg)](https://github.com/AY2021S2-CS2103T-W15-1/tp/actions)
+[![codecov](https://codecov.io/gh/AY2021S2-CS2103T-W15-1/tp/branch/master/graph/badge.svg)](https://codecov.io/gh/AY2021S2-CS2103T-W15-1/tp)
 
 ![Ui](docs/images/Ui.png)
 
@@ -12,3 +13,13 @@
 * It is named `AddressBook Level 3` (`AB3` for short) because it was initially created as a part of a series of `AddressBook` projects (`Level 1`, `Level 2`, `Level 3` ...).
 * For the detailed documentation of this project, see the **[Address Book Product Website](https://se-education.org/addressbook-level3)**.
 * This project is a **part of the se-education.org** initiative. If you would like to contribute code to this project, see [se-education.org](https://se-education.org#https://se-education.org/#contributing) for more info.
+
+### Site Map
+[User Guide](docs/UserGuide.md)
+
+[Developers Guide](docs/DeveloperGuide.md)
+
+[About Us](docs/AboutUs.md)
+
+### Acknowledgement
+* This project is based on the AddressBook-Level3 project created by the [SE-EDU initiative](https://se-education.org).