docs: fix typo in korean documentation

[kshired]

Motivation

There are typos in the Korean documentation

Modifications

• fix typo in README.md and expressions.md

Commit Convention Rule

• Please commit your modification based by conventional commit:

Commit type	Description
feat	New Feature
fix	Fix bug
docs	Documentation only changed
ci	Change CI configuration
refactor	Not a bug fix or add feature, just refactoring code
test	Add Test case or fix wrong test case
style	Only change the code style(ex. white-space, formatting)
chore	It refers to minor tasks such as library version upgrade, typo correction, etc.

• If you want to add some more commit type please describe it on the Pull Request

Result

• Fixed typo

Closes

• N/A

[CLAassistant]

All committers have signed the CLA.

[shouwn]

Thanks for your help!