Add development to environments for yml file
Add development to environments for yml file

This makes this onboarding easier for people testing their first
requests in development mode. It also follows the Rails defaults.

appsignal/appsignal-ruby,matrinox/appsignal-ruby,appsignal/appsignal-ruby,matrinox/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal,matrinox/appsignal-ruby,appsignal/appsignal-ruby,appsignal/appsignal