[Cherrypick 2.0] Update to_tensor docs#29901

Merged

jzhang533 merged 1 commit intoPaddlePaddle:release/2.0from LielinJiang:cherrypick-to-tensor-docs

Dec 25, 2020

+15-9

Commits on Dec 25, 2020

Update en docs of to_tensor (PaddlePaddle#29718 )
LielinJiang
committed