[Docs] Add TRANSLATING.md file (#1920)
* init for korean docs
* edit build yml file for multi language docs
* edit one more build yml file for multi language docs
* add title for get_frontmatter error
* add translating.md
* default language for docs is en
* Update docs/TRANSLATING.md
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
