fix(docs): add missing extension for Contributing link (#83)

Author: edoko

README.md

@@ -190,7 +190,7 @@ You can use the `@callstack/licenses` package to access the core functionalities
 
 ## Contributing
 
-See the [contributing guide](./CONTRIBUTING) to learn how to contribute to the repository and the development workflow.
+See the [contributing guide](./CONTRIBUTING.md) to learn how to contribute to the repository and the development workflow.
 
 ## Acknowledgements