Fix docs pointers for DeepSpeed

[marctorsoc]

In this section, the reader is pointed to several links that are broken:

• https://huggingface.co/docs/transformers/master/en/main_classes/trainer#deepspeed-trainer-integration
• https://huggingface.co/docs/transformers/master/en/main_classes/trainer#deepspeed-installation
• https://huggingface.co/docs/transformers/master/en/main_classes/trainer#deepspeed-multi-gpu
• https://huggingface.co/docs/transformers/master/en/main_classes/trainer#deepspeed-one-gpu
  *https://huggingface.co/docs/transformers/master/en/main_classes/trainer#deepspeed-config-passing
• etc

All of them should be changed like this:

https://huggingface.co/docs/transformers/master/en/main_classes/trainer#(.*) --> https://huggingface.co/docs/transformers/master/en/main_classes/deepspeed#(.*)

I would do it myself, but I see that the code uses e.g. :ref:deepspeed-notebook` and not sure how to point to a section in another page 🤷‍♂️ It looks like a trivial change though

[LysandreJik]

If I'm not mistaken this is patched on master and will be reflected soon on the documentation cc @sgugger

[marctorsoc]

@LysandreJik At least in this line: https://github.com/huggingface/transformers/blame/master/docs/source/main_classes/trainer.rst#L506, it seems to be still outdated. Are you sure this is patched?

[sgugger]

I will push a patch later today.