Add pinning_version / version to README
Add pinning_version / version to README

joeyAghion/chef-td-agent,treasure-data/chef-td-agent,PerfectMemory/chef-td-agent,i/chef-td-agent,benvaljean/chef-td-agent,i/chef-td-agent,benvaljean/chef-td-agent,ikkyotech/OpsworksNodeAddons,ijin/chef-td-agent,ikkyotech/OpsworksNodeAddons,treasure-data/chef-td-agent,joeyAghion/chef-td-agent,PerfectMemory/chef-td-agent,treasure-data/chef-td-agent,ijin/chef-td-agent