docs: added documentation link

Author: Mazzya

README.md

@@ -86,7 +86,7 @@ $ {
 
 ```
 ## Documentation
-To learn more about the library, please visit our official [documentation]().
+To learn more about the library, please visit our official [documentation](https://qubipy.readthedocs.io/en/latest/).
 
 ### Notes
 This library is using `crypto.dll` which is a C extension of Qubic key utility functions and bind it to Python. To build this `crypto.dll`, this repository was used: [https://github.com/serendipity-seeker/key-utils-binding](https://github.com/serendipity-seeker/key-utils-binding).