[deepspeed] offload + non-cpuadam optimizer exception doc
part 2 of https://github.com/huggingface/transformers/pull/22043, but we can't merge it until `deepspeed==0.8.3` is released.

This PR documents the new feature and up's the min deepspeed version.

**XXX: DO NOT MERGE UNTIL `deepspeed==0.8.3` is released.**

I'm keeping it as a DRAFT so that I don't mistakenly merge it to soon. But we can pre-approve.

cc: @jeffra 
_The documentation is not available anymore as the PR was closed or merged._