Doc needs updating with existing configuration options

[esciara]

Hi there,

There are some features that are not documented anywhere, such as the one introduced in 6e30431 (which introduced several more):

provisioner:
  name: chef_solo
  solo_rb:
    http_proxy: http://192.168.1.1
    https_proxy: http://192.168.2.2

I was looking for that kind of configuration options, but could neither find it on http://kitchen.ci/, nor on http://docs.opscode.com/config_yml_kitchen.html. Took me a while to unearth it.

Is there any other neat stuff hidden like that?

[cheeseplus]

Between http://kitchen.ci/docs/kitchen-examples and https://docs.chef.io/config_yml_kitchen.html these should all now be covered.