Added region information to S3 bucket creation step

[Stallians]

Hi Joseph,

I tried running the setup_infra.sh on my machine & found that region information is required to create the bucket. This is a mandate except the region US Ease (N. Virginia)

Additionally, I thought it would be better if this information can be asked at the time of script invokation. Hence I asked for region information as an additional parameter along with exising bucket_name.

Thanks,
Stallians

References:

1. AWS CLI documentation
2. Stack Overflow issue

[josephmachado]

tyvm @Stallians

[Stallians]

Update readme appropriately.