Add korean translation of README.md

[KIMMINTAE98]

What is it?

• Bugfix (user facing)
• Feature (user facing)
• Codebase improvement (dev facing)
• Meta improvement to the project (dev facing)

Description of the changes in your PR

• Added README_KO.md which is korean translation of README.md
  to active the participation of the Korean contributors or download of Korean users.

Due diligence

• I read the contribution guidelines.

[Stypox]

Is this the standard way to provide a translated README for GitHub repositories? Will Korean users automatically see it when opening the repo?

[opusforlife2]

@Stypox See for example https://github.com/tiimgreen/github-cheat-sheet/blob/master/README.md which contains links to translated versions of itself.

However, it uses README.ko.md instead of README_KO.md like Min-Tae has done here.

[Stypox]

@KIMMINTAE98 thank you! Can you rename the file to README.ko.md as requested by opusforlife2? Then this can be merged, can't it @B0pol @opusforlife2?

[opusforlife2]

@Stypox Note that I haven't found any official Github documentation on this. What I've said above is just from researching what seem to be the best practices in other repos.

[B0pol]

@Stypox no, in README.md there shoul be a line like "korean translation", otherwise nobody will know about this translation.

Also, why are section titles not translated?

[opusforlife2]

@B0pol The Readme I linked has:

Read this in other languages: English, 한국어, 日本語, 简体中文, 正體中文.

We could add that to our Readme.

[Stypox]

Thank you!