docs

* first commit of op floor

* first commit of op acos

* split acos from math_ops and add doctest

* resolve conflicting files

* fix format bug

* auto format by CI

* add check license

* synchronize local with remote

* auto format by CI

* first commit of op acos

* Update tensor.cpp

* solve conflicts

* add of_softmax_use_fast_math (#4979)

Co-authored-by: oneflow-ci-bot <69100618+oneflow-ci-bot@users.noreply.github.com>

* auto format by CI

* ci check license

Co-authored-by: Luyang <flowingsun007@163.com>
Co-authored-by: Xiaoyu Zhang <35585791+BBuf@users.noreply.github.com>
Co-authored-by: oneflow-ci-bot <69100618+oneflow-ci-bot@users.noreply.github.com>
Co-authored-by: oneflow-ci-bot <ci-bot@oneflow.org>
Co-authored-by: JiaojiaoYe1994 <jiaojiaoye@tum.de>