Update docs to include testing deregistration/keepalive handlers

[asachs01]

Description

In an ideal world, we'd have some example keepalive events to help users test when they have an issue with keepalives/deregistration.

Category

This is an issue with:

• [ ] errata (error in doc content)
• [ ] new doc (requires a completely new doc)
• [ ] update (add missing or refresh existing content)
• [x] improvement (improve docs content or format)