Clarify Rails 3.0 support comment
Clarify Rails 3.0 support comment

kewaunited/shopify_app,egowens/shopify_app,mig1098/shopify_app,Shopify/shopify_app,icodedev7/development,Shopify/shopify_app,egowens/shopify_app,Shopify/shopify_app,icodedev7/development,mig1098/shopify_app,egowens/shopify_app,kewaunited/shopify_app,nwallace/shopify_app,Shopify/shopify_app,nwallace/shopify_app