Updated the documentation links

docs/index.md

@@ -5,7 +5,7 @@
 
 PHP Chess Server is an asynchronous PHP server that provides functionality to play chess online over a WebSocket connection.
 
-Similar to the [PHP Chess API](https://chess-api.docs.chesslablab.org/), it can be hosted on a custom domain. However, while the API endpoints may take few seconds to execute — for example, a file download or a database query — the event-driven, non-blocking architecture of the chess server allows to handle multiple concurrent connections in an efficient way.
+Similar to the [PHP Chess API](https://chesslablab.github.io/chess-api/), it can be hosted on a custom domain. However, while the API endpoints may take few seconds to execute — for example, a file download or a database query — the event-driven, non-blocking architecture of the chess server allows to handle multiple concurrent connections in an efficient way.
 
 The chess commands are intended to run very quickly almost in real-time.