small revision to S3 Bucket Configuration readme

[runningonsideprojects]

Increasing Access

Making any additional clarifications to the documentation instructions would increase access writ large to contributions to or engagement with the web editor.

Feature enhancement details

I was following the instructions to the S3 Bucket Configuratin Readme. And am requesting to have instruction 4 go before instruction 3.

In my experience setting up the buckets, you cannot perform instruction 3 (make changes to the bucket policy) until you make the changes outlined in instruction 4 (unblock access to bucket settings).

In my experience, when you try and implement instruction 3 without instruction 4, you receive this following error:

This a nit, and it was easy to figure out what was going on, but changing the order would reduce any confusion!

[runningonsideprojects]

@raclim i can also take this one!