Codify working and non-working s3 url examples in the README

[ghost]

The s3 section in the README links to https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-bucket-intro.html
In that page it has examples of virtual-hosted style access, the deprecated path-styl-access, neither of which work with go-getter (apparently because of the http:// or https:// scheme at the beginning of the urls). This also means that the object url link in the s3 page does not work for the same reason. Surprisingly the s3:// mentioned in https://docs.aws.amazon.com/AmazonS3/latest/userguide/access-bucket-intro.html#accessing-a-bucket-using-S3-format does work, but isn't mentioned in the examples.

Ideally the examples would show what does work, and then examples of what does not work ie something like

Supported formats:

• virtual-host style without http protocol prefix
  • bucket.s3.amazonaws.com/foo
  • bucket.s3-eu-west-1.amazonaws.com/foo/bar
• path-based style without http protocol prefix
  • bucket.s3-eu-west-1.amazonaws.com/foo/bar
• s3 protocol
  • s3://s3.amazonaws.com/bucket/foo
• forced protocol without http protocol prefix
  • s3::s3.amazonaws.com/bucket/foo
  • s3::s3-eu-west-1.amazonaws.com/bucket/foo
• forced protocol with http protocol prefix
  • s3::https://s3.amazonaws.com/bucket/foo
  • s3::https://s3-eu-west-1.amazonaws.com/bucket/foo
  • "s3::http://127.0.0.1:9000/test-bucket/hello.txt?aws_access_key_id=KEYID&aws_access_key_secret=SECRETKEY&region=us-east-2"

Unsupported formats (will NOT work)

• virtual-host style with http protocol prefix
  • https://bucket.s3.amazonaws.com/foo
  • bucket.s3-eu-west-1.amazonaws.com/foo/bar

As a sidenote, it would be really nice if go-getter did work for s3 URLs when they are prefixed with http:// or https://.