Documents docker image flow

[bmuenzenmeyer]

Description

Documents docker image flow. I elected not to use mermaid as I thought it was a bit too limiting.

Motivation and Context

I get asked this question often. With the most recent security release, I was asked three times within my company how this works.

I talked to @nschonni within #2339 to get some initial alignment.

Testing Details

Example Output(if appropriate)

Types of changes

• Documentation
• Version change (Update, remove or add more Node.js versions)
• Variant change (Update, remove or add more variants, or versions of variants)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Other (none of the above)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING.md document.
• All new and existing tests passed.