Fix: fix wrong path to API spec

Author: tollsimy

openapi.yaml

@@ -7,7 +7,7 @@ info:
 
     Some useful links:
     - [Open Park Project](https://github.com/OpenParkProject)
-    - [API definition](https://github.com/OpenParkProject/OPP-common/openapi.yaml)
+    - [API definition](https://raw.githubusercontent.com/OpenParkProject/OPP-common/refs/heads/main/openapi.yaml)
 
   contact:
     email: tollsimy.dev@protonmail.com