Add Korean Translation

[evan-hwang]

Description

I'm adding a translation for a Korean developer.
I am also a Korean developer.
I translated it because Korean developers love the project so much. Thank you. 🙏

I interpreted the word "Streak" as "work that I've been doing."
So I translated 'Current Streak' into 'Current Continuous Commit Count' and 'Longest Streak' into 'Maximum Continuous Commit Count'.

Fixes #236

Type of change

• Bug fix (added a non-breaking change which fixes an issue)
• New feature (added a non-breaking change which adds functionality)
• Updated documentation (updated the readme, templates, or other repo files)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Tested locally with a valid username
• Tested locally with an invalid username
• Ran tests with composer test
• Added or updated test cases to test new features

Checklist:

• I have checked to make sure no other pull requests are open for this issue
• The code is properly formatted and is consistent with the existing code style
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

Screenshots