document of entropy injection may mislead users

FLINK-9061 incroduce entropy inject to s3 path for better scalability, but in document of entropy-injection-for-s3-file-systems use a example with checkpoint directory "s3://my-bucket/checkpoints/entropy/dashboard-job/", with this configuration every checkpoint key will still start with constant checkpoints/ prefix which actually reduces scalability.

Thanks to dmtolpeko for describing this issue in his blog ( flink-and-s3-entropy-injection-for-checkpoints ).

Proposal

alter the checkpoint directory in document of entropy-injection-for-s3-file-systems to "s3://my-bucket/entropy/checkpoints/dashboard-job/" (make entropy key at start of keys).

If this proposal is appropriate, I am glad to submit a PR to modify the document here. Any other ideas for this ?