Add comments in init_system custom fact

lib/facter/init_system.rb

@@ -1,25 +1,37 @@
 Facter.add(:init_system) do
   confine :kernel => 'Linux'
   setcode do
+
+    # Active init system process has PID 1
     proc_1 = Facter::Core::Execution::exec('ps --no-headers -p 1').split(' ')[-1]
+
+    # A PID 1 process called `init` can be a link to systemd or upstart
     unless proc_1 == 'init'
       proc_1
     else
       path_exec = Facter::Core::Execution::exec("ls -l $(which #{proc_1})").split(' ')[-1]
       file_exec = path_exec.split('/')[-1]
+
+      # An executable called `init` can be a link to systemd or upstart
       unless file_exec == 'init'
         file_exec
       else
+
+        # Check package which provided running init system executable
         case Facter.value(:osfamily)
         when 'Debian', 'Ubuntu'
           pkg_exec = Facter::Core::Execution::exec("dpkg-query -S #{path_exec}").split(' ')[0]
         when 'RedHat'
           pkg_exec = Facter::Core::Execution::exec("rpm -qf #{path_exec}").split('-')[0]
+        # TODO: add similar checks for other distros
         else
           pkg_exec = 'unknown'
         end
         pkg_exec.downcase[/systemd|upstart|init|unknown/]
+
       end
+
     end
+
   end
 end