OS resource requires requires a Symbol not a String (wrong in docs)

[stuartpreston]

Platform: Windows 10/ChefDK 0.9/InSpec 0.9 + Test Kitchen/AzureRM driver/Windows 2012 R2 Datacenter instance.

As per https://docs.chef.io/release/compliance_1-0/inspec_os.html

Input:

describe os['family'] do
  it { should eq 'windows' }
end

Outcome:

  1)  should eq "windows"
     Failure/Error: it { should eq 'windows' }

       expected: "windows"
            got: nil

       (compared using ==)

Correct usage appears to be:

describe os[:family] do
  it { should eq 'windows' }
end

Submitting a doc PR for this shortly.