{:credentials #:aws{:access-key-id "some-access-key"
               :secret-access-key "wild_secr3t"
               :session-token "FwoG..."}
 :region "us-east-1"
 :endpoint {:protocol :https
            :hostname "s3.amazonaws.com"}}

Relevant AWS documentation:

- https://docs.aws.amazon.com/AmazonS3/latest/API/sig-v4-header-based-auth.html
- https://docs.aws.amazon.com/AmazonS3/latest/userguide/RESTAuthentication.html

When the documentation references a client it is either a [awyeah][1] client,
a [Cognitect AWS API][2] client or a map with the following structure:

    {:credentials #:aws{:access-key-id "some-access-key"
                   :secret-access-key "wild_secr3t"
                   :session-token "FwoG..."}
     :region "us-east-1"
     :endpoint {:protocol :https
                :hostname "s3.amazonaws.com"}}

Notice: `:endpoint` is optional.

[1]: https://github.com/grzm/awyeah-api
[2]: https://github.com/cognitect-labs/aws-api