Create an S3 bucket as follows:

aws s3api create-bucket 
    --bucket serverlesscookbook-cognito-files 
    --profile admin

Upload the amazon-cognito-identity.min.js file:

aws s3 cp amazon-cognito-identity.min.js s3://serverlesscookbook-cognito-files 
    --profile admin

Execute the bucket policy that allows public read access to the bucket:

aws s3api put-bucket-policy 
    --bucket serverlesscookbook-cognito-files 
    --policy file://s3-website-policy.json 
    --profile admin

The s3-website-policy.json file should have these contents:

{  "Version":"2012-10-17",
    "Statement":[
        {    "Sid":"PublicReadGetObjectAccess",
            "Effect":"Allow",
            "Principal": "*",
            "Action":["s3:GetObject"],
            "Resource":["arn:aws:s3:::serverlesscookbook-cognito-files/*"]
        }  ]
}