Versioning Docs

[oubiwann]

• Identify open source projects that have versioned docs well - Identify open source projects that have versioned docs well #67
• Devise a URL schema for current and versioned docs
• Devise a mechanism for versioning docs - Devise a mechanism for versioning docs #38
• Figure out the impact on existing URLs if docs are moved behind /current

Part of Milestone v3 #62

[oubiwann]

Done. We're already publishing with them.