How to translate and contribute

Create a new directory and name it to the short language code. e.g. for Germany, please name it de_DE.
Add file de_DE/_lang.md with the full name of the language. e.g. write English in en_US/_lang.md, 简体中文 in zh_CN/_lang.md.
Copy the markdown document you want to translate to new language directory, create the same sub-directories as original document. For example, to translate en_US/howto/reset.user.password.md, please create de_DE/howto/ and copy reset.user.password.md to de_DE/howto/.
Translate the file and send a pull request.