Clarify if version labels for subgraph deployments have to be unique

Here: https://thegraph.com/docs/en/subgraphs/developing/deploying/using-subgraph-studio/#deploying-a-subgraph It's not mentioned if the version labels have to be unique. <img width="400" alt="Image" src="https://github.com/user-attachments/assets/ac350689-6a01-4f6c-a063-eed25a2c836a" />