Document how to configure S3 Express buckets

Stan Hurequested to merge
sh-s3-express-docs into main

What does this MR do?

GitLab Runner v17.5.0 switched to the AWS SDK for S3 cache access: !4987 (merged). This added support for S3 Express One Zone buckets. This documents how to use them.

Note that RoleARN does not work with these buckets.

Relates to #38484 (closed)

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Edited by Stan Hu

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