✏️ Fix minor typos in `docs/ko/docs/`

[KaniKim]

• Change "경로 동작" to "경로 작동" as discussed in https://github.com/tiangolo/fastapi/discussions/3167#discussioncomment-721448
• Change tip and note typo and etc
• docs/ko/docs/tutorial/background-tasks.md, docs/ko/docs/tutorial/body-fields.md, docs/ko/docs/tutorial/body-multiple-params.md, docs/ko/docs/tutorial/dependencies/classes-as-dependencies.md, docs/ko/docs/tutorial/first-steps.md and etc

[tiangolo]

📝 Docs preview for commit d6a79600937bfc9cee244f35ad76922d68fe4d7f at: https://08bb4c43.fastapitiangolo.pages.dev

[alejsdev]

Nice, thanks @KaniKim 🧐🔍

And thanks for the review @riroan 🎉