Add both vuln and Vuln

Signed-off-by: imjoseangel <josea.munoz@gmail.com>

Author: imjoseangel

controls/os_spec.rb

@@ -253,7 +253,8 @@
 
     loaded_files.each do |vulnfile|
       describe file(vulnfile) do
-        its('content') { should_not match 'vulnerable' }
+        its(:content) { should_not match 'vulnerable' }
+        its(:content) { should_not match 'Vulnerable' }
       end
     end
   end