[chat] ChatGPT train prompts on ray example

[MisterLin1995]

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[SongGuyang]

I has some suggestions:

• Do we need an independent directory for the code about ray integration? E.g. applications/Chat/experimental/ray/
• We can use ray.wait instead of ray.get when we should wait a lot object refs. In this way, you can set wait timeout and it is easy to debug. (We can also optimize this in the following works, don't block current PR)
• We can add a design doc or design graph to explain the architecture.（don't block current PR）

[ver217]

Can you move your files to Chat/examples/community/ray first? And you can update the README.