Add mechanism for adding doc translations

[RusinovAnton]

The draft spec on the translation mechanism:

• each docs translation should have a separate folder, named by its language code in ISO 639-1 format:

docs/
  en/...
  he/...
  ...

• there should be a separate index.json and search-index.json per each language.
  The current process of the building of the doc sheet path should be changed. path property should be computed using the convention: /docs/${language}/${domainName}/${method/property -Name}

• language code should be added in the route path and read from there.
  I would really like to have separate subdomains, but I just cannot afford it at this moment
  We might want to have no language code for the English version to keep URL simple. Also, see Simplify docs' URL #102
  Examples:

  • https://js-tldr.info/docs/ - for English
  • https://js-tldr.info/he/docs/ - for Hebrew
  • https://js-tldr.info/uk/docs/ - for Ukrainian

[AlinaAlef]

🙋🏽‍♀️