docs: restore WeightNz FP8 support notes-ops-nn-AtomGit

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已合并

docs: restore WeightNz FP8 support notes #5874

Hu1L1创建于 6月9日从Hu1L1/ops-nn： doc/weightnz-split 合入到 cann/ops-nn： master

docs: restore WeightNz FP8 support notes #5874

已合并

Hu1L1创建于 6月9日

从Hu1L1/ops-nn doc/weightnz-split合入到cann/ops-nn master