README: added IAM roles link
README: added IAM roles link

zuazo/chef-handler-sns,mixpanel-platform/chef-handler-sns,easybiblabs/chef-handler-sns,mevic/chef-handler-sns,onddo/chef-handler-sns,zuazo/chef-handler-sns,mevic/chef-handler-sns,mixpanel-platform/chef-handler-sns,onddo/chef-handler-sns