Clarify discussion of CloudFront origin

[smalers]

The following text was in the documentation but is confusing and has been removed:

Note that this example uses the origin content of the S3 bucket, not the served static website.
This is done on purpose to illustrate how to resolve the issue with `index.html` not being the default file in a folder when using CloudFront.

I think we needed to use the S3 bucket for the CloudFront origin and not the URL to the S3 site (probably the internal URL?). Maybe try an experiment when there is time. I think the bigger issue is that for single page applications we needed to deal with base href. Figure out if this text is relevant or not.