Add a section about cleaning the bucket

[Amri91]

This PR has been moved from aws/aws-sam-cli#666

Resolves aws/aws-sam-cli#648

Issue #, if available:
aws/aws-sam-cli#648

Description of changes:
Added a section to show how to clean the bucket.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[Amri91]

I forced pushed to change the cleaning behaviour. Thanks to Romain Marcadier-Muller (AWS) from the AWS samdev slack channel for clearing up the confusion.

[mark-hirayama]

Thank you @Amri91 for submitting this doc PR. After discussing internally with members of the sam cli dev team, it was determined that there are certain use cases that require these packaged S3 objects to persist, and deleting them would cause significant problems. One such example is the "CloudFormation stack deployment rollback" scenario: 1) Deploy version N of a stack, 2) Delete the packaged S3 object that version N uses, 3) Deploy version N+1 with a "bad" template file that triggers a CloudFormation rollback. Because of this, this doc PR will not be merged into the docs. The right next step is for the sam cli dev team to prioritize a "delete unused packaged S3 objects" feature that includes appropriate safeguards that verify objects will not ever be needed again before deleting them.

[jlk]

There's a lot of good docs in this repo, it's too bad s3 management isn't addressed.

Maybe instead of rejecting this PR, suggestions could be made to improve it to cover the use cases mentioned? Perhaps suggest setting the expiration to a week or a month vs a day.

This ticket's been closed for 2+ years, as far as I can tell the mentioned "right step" hasn't happened. Some docs could have helped many people in this period...