[data-source][rhoas-kafkas] Fix example

[juandspy]

Summary

Fixing #28.

Testing steps

make install
cd examples/data-sources/rhoas_kafkas
terraform init
terraform plan

Output

Changes to Outputs:
  + all_kafkas = {
      + id     = "1664374818"
      + kafkas = [
          + {
              + bootstrap_server_host = "XXXXXXXXXXX"
              + cloud_provider        = "aws"
              + created_at            = "XXXXX"
              + failed_reason         = ""
              + href                  = "/api/kafkas_mgmt/v1/kafkas/XXXXXXXXXXX"
              + id                    = "XXXXXXXXXXXXXXXX"
              + kind                  = "Kafka"
              + multi_az              = false
              + name                  = "test"
              + owner                 = "jdiazsua@redhat.com"
              + region                = "eu-west-1"
              + status                = "ready"
              + updated_at            = "XXXXX"
              + version               = "3.2.1"
            },
          ...
        ]
    }

You can apply this plan to save these new output values to the Terraform state, without changing any
real infrastructure.

[jackdelahunt]

👍