Document limitations with headless services and load balancing policies

[nstuart-idexx]

Describe the feature request
It's not clear anywhere in the documentation that load balancing destination rules don't actually work. I believe I understand why it doesn't work, but it would have been great to not have to figure that out through discovery/troubleshooting.

If this already is documented somewhere, please point me to those docs, the only thing I could actually find online was in someone else's FAQs here.

Affected product area (please put an X in all that apply)

[ ] Ambient
[X] Docs
[ ] Dual Stack
[ ] Installation
[ ] Networking
[ ] Performance and Scalability
[ ] Extensions and Telemetry
[ ] Security
[ ] Test and Release
[ ] User Experience
[ ] Developer Infrastructure