Proposal: Restructure docs to accomodate localization.

Goal:

• Existing English URLs are unchanged. They should be available athttp://expressjs.com/en/foo/bar.html as well ashttp://expressjs.com/foo/bar.html.
• Localized content provided athttp://expressjs.com/xx, where xx is the ISO lang code, e.g.http://expressjs.com/jp for Japanese. So for example URLS would be e.g.http://expressjs.com/starter/installing.html -->http://expressjs.com/jp/starter/installing.html.

This would require some restructuring of the repository.

NOTE: We arenot proposing localization of 3.x or 2.x docs.

The following are all top-level directories:

• 4x
• en/api - NOTE: This is the only directory with a lang code.
• advanced
• api.html
• api.jade
• guide
• includes
• index.html
• index.jade
• resources
• starter

• en
• 4x (content from currenten/api )
• 3x
• 2x
• advanced
• api.html
• api.jade
• guide
• includes
• index.html
• index.jade
• resources
• starter
• jp
• 4x
• advanced
• api.html
• api.jade
• guide
• includes
• index.html
• index.jade
• resources
• starter
• fr
• ....

NOTE: The following content would not be translated (along with obvious stuff like package.json):

• 2x
• 3x
• images
• css
• js
• fonts