docs: clarify setup env for development.

[iFurySt]

#51

[CLAassistant]

All committers have signed the CLA.

[tianjing-li]

@iFurySt same thing here, you'll need to resign the commits - For future PRs you can run git config --global commit.gpgSign true to always sign

[iFurySt]

okay, it's been updated.

[tianjing-li]

@iFurySt merging