🌐 Fix Korean translation for docs/ko/docs/index.md

[kty4119]

Thank you always for your hard work.
I found something good to fix in this file.

• Change the expression that doesn't match.
• changed it according to the guidelines.

@hard-coders
Please check if this modification is appropriate and leave a comment.
Thank you for your hard work.

This PR complements docs/ko/docs/index.md
related : #2017

[DevDae]

Thank you for your works.
Please check my PR too! 😄

[hard-coders]

This PR is following the rules better. Thank you for your effort.

[NinaHwang]

LGTM 🚀

[tiangolo]

Awesome, thank you @kty4119! 🍰

And thanks for the reviews @hard-coders, @NinaHwang, @DevDae. 🙇 ☕

[codecov]

Codecov Report

Merging #4195 (9daf262) into master (0a61a6c) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##            master     #4195     +/-   ##
===========================================
  Coverage   100.00%   100.00%             
===========================================
  Files          409       504     +95     
  Lines        10264     12707   +2443     
===========================================
+ Hits         10264     12707   +2443     

Impacted Files	Coverage Δ
fastapi/utils.py	100.00% <0.00%> (ø)
fastapi/applications.py	100.00% <0.00%> (ø)
fastapi/openapi/docs.py	100.00% <0.00%> (ø)
...test_tutorial/test_dataclasses/test_tutorial002.py	100.00% <0.00%> (ø)
..._tutorial/test_sql_databases/test_sql_databases.py	100.00% <0.00%> (ø)
...orial/test_sql_databases/test_testing_databases.py	100.00% <0.00%> (ø)
docs_src/app_testing/main_b.py
docs_src/app_testing/test_main_b.py
...utorial/test_body_updates/test_tutorial001_py39.py	100.00% <0.00%> (ø)
docs_src/extra_models/tutorial005_py39.py	100.00% <0.00%> (ø)
... and 95 more

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