ZeRO 2 configuration example

[CHN-ChenYi]

📚 The doc issue

The gpt2 zero2 example was removed after the new API was introduced.
But I don't know how to not offload the model.
I've tried removing model_config or setting offload_config to None/gpu/cuda, but neither of them works.

[binmakeswell]

Hi @CHN-ChenYi , we have update the example and tutorial, you can directly use zero, and do not need to set level 2.

https://github.com/hpcaitech/ColossalAI-Examples/tree/main/features/zero
https://www.colossalai.org/docs/features/zero_redundancy_and_zero_offload