create new docs structure

[jackzampolin]

Originally: https://github.com/influxdb/influxdb.com/issues/329

In advance of the new website and docs support for the new products, let's build the skeleton organization.

Each product will have the following sections:

• Intro
  • Overview
  • Installation
  • Getting Started
• Learning (replaces Guides)
• Reference (can be multiple sections here)
  • Configuration
  • Plugins (if appropriate)
  • Libraries (if appropriate)
  • DSL (if appropriate)
• About
  • Contributing
  • License
  • Getting Help