Distributed Tracing feature in PHP Agent cookbook doesn't work

[alexkokkinos]

Setting node['newrelic']['application_monitoring']['distributed_tracing_enabled'] = true or node['newrelic']['application_monitoring']['distributed_tracing_exclude_newrelic_header'] = true fails to modify newrelic.ini to set newrelic.distributed_tracing_enabled or newrelic.distributed_tracing_exclude_newrelic_header to true, respectively.

I will be submitting a PR for this correction shortly.

386 introduced this feature