Complete the doc with a doc corresponding to the whole project

Passing from a menu like this : 
> Component 1
      - docfile 1
      - docfile 2
      - API
> Component 2
> Component 3

To : 
> Getting started (with Objective v2)
     - Starter kit
     - Start server
     - Configuration
> Components
      > Component 1
      > Component 2
      > Component 3
> Tutorials (why not)
     - Write a new command with Objective CLI
     - ...
