added README.md mention of node['splunk']['ratelimit_kilobytessec']
added README.md mention of node['splunk']['ratelimit_kilobytessec']

Springworks/chef-splunk,Sauraus/chef-splunk,Springworks/chef-splunk,chef-cookbooks/chef-splunk,chef-cookbooks/chef-splunk,GannettDigital/chef-chef-splunk,GannettDigital/chef-chef-splunk,Springworks/chef-splunk,rarsan/chef-splunk,rarsan/chef-splunk,GannettDigital/chef-chef-splunk,sworisbreathing/chef-splunk,sworisbreathing/chef-splunk,rarsan/chef-splunk,Sauraus/chef-splunk,chef-cookbooks/chef-splunk,Sauraus/chef-splunk,sworisbreathing/chef-splunk