[Docs](mlu-ops): Update v1.9.1 docs

[duzekunKTH]

Thanks for your contribution and we appreciate it a lot. 🚀🚀

1. Motivation

Please describe your motivation and the goal you want to achieve through this pull request.

2. Modification

modified:   build.property
modified:   docs/api_guide/update.rst
modified:   docs/release_notes/mlu_ops.rst
modified:   docs/user_guide/2_update_history/index.rst
modified:   mlu_op.h

3. Test Report

no test

[DanieeelLiu]

LGTM

[Clearlove-Inf]

LGTM