New speed documentation (#7665)

* amp

* amp

* docs

* add guides

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* amp

* amp

* docs

* add guides

* speed guides

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Delete ds.txt

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* Update conf.py

* Update docs.txt

* remove 16 bit

* remove finetune from speed guide

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* speed

* speed

* speed

* speed

* speed

* speed

* speed

* speed

* speed

* speed

* speed

* speed

* remove early stopping from speed guide

* remove early stopping from speed guide

* remove early stopping from speed guide

* fix label

* fix sync

* reviews

* Update trainer.rst

* Update trainer.rst

* Update speed.rst

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