[docs] Fix link (#6029)

Update repository_structure.mdx

Author: stevhliu

docs/source/repository_structure.mdx

@@ -146,7 +146,7 @@ configs:
 ---
 ```
 
-Refer to [specific builders' documentation](.package_reference/builder_classes) to see what configuration parameters they have.
+Refer to [specific builders' documentation](./package_reference/builder_classes) to see what configuration parameters they have.
 
 <Tip>