Add comment about sudo false Travis config

Author: bcrowe

.travis.yml

@@ -7,6 +7,8 @@ php:
   - 7.0
   - hhvm
 
+# This triggers builds to run on the new TravisCI infrastructure.
+# See: http://docs.travis-ci.com/user/workers/container-based-infrastructure/
 sudo: false
 
 matrix: