[Docs] Fix docs and breaking var name typos

[bryce-evans]

Fixes various grammar and spelling mistakes, some breaking (in the case of support_opset_verision_range support_opset_verison_range)

[CLAassistant]

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[Zheng-Bicheng]

@jiangjiajun This PR does not involve the source code of Paddle2ONNX and can be directly integrated. But the contributor did not sign the cla agreement, can we merge this PR?