Clarify benchmark text

Previous wording sounded like s3 support was being dropped, when it was the dependency group. Updated this to reflect the "s3" group support would be dropped in favour of "cloud"

Author: kaitj

README.md

@@ -23,7 +23,7 @@ pip install bids2table[cloud]
 ```
 
 > [!WARNING]
-> Previous version only supported s3. s3 installation is still supported, but will be deprecated in the next version. Please update any installation scripts.
+> Previous version only supported s3 cloud storage. `s3` dependency group installation is still supported, but will be deprecated in the next version. Please update any installation scripts to use the `cloud` dependency group.
 
 The latest development version can be installed with