How to translate and contribute

Create a new directory and name it to the short language code. e.g. for Germany, please name it zh_CN.
Add file zh_CN/_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 zh_CN/howto/ and copy reset.user.password.md to zh_CN/howto/.
Translate the file and send a pull request.