Add documentation for using lifecycle (EOL) annotations

[lbussell]

Describe the Problem

Image lifecycle annotations are being added to images as part of Add lifecycle annotations to images pushed to MCR (docker-tools#1201).

Describe the Solution

We should have guidance in this repo's documentation for using these annotations. It should probably include:

1. How to determine if a given image is out-of-date/EOL using lifecycle annotations
2. How to determine when the image went out of date/when the annotation was created
3. How to find the latest image if you are referencing an EOL image by its digest

Additional Context

Helpful link for whoever documents this: CSSC [MSFT internal link]

[lbussell]

[Triage] This could improve the UX of the Container vulnerability workflow document as the ORAS commands could replace some of our custom scripts that we use to determine if images are out-of-date or not.