fix: Grammartical error typo in readme_kr.md

[rjsdn0124]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

I changed black space between the words.

Does this PR introduce a breaking change?

• Yes
• No

Other information

It's my first PR to big repository like here.. So thank you :)

[coveralls]

Pull Request Test Coverage Report for Build 6f97b560-5110-4d72-8dc3-e439be5494dd

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 93.786%

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Totals
Change from base Build 6b637f64-9c7a-4d7b-8537-b6a8d098f58e:	0.0%
Covered Lines:	6113
Relevant Lines:	6518

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💛 - Coveralls