lua-bridge-tracer example for openresty nginx

[ghost]

I've tried to get the lua block traced in openresty nginx and the setup works without errors but I do not see any lua span in datadog. Might be worth having an example for this setup.

https://github.com/opentracing/lua-bridge-tracer

Have an example for datadog next to jaeger and lightspeed.. Cfr https://github.com/opentracing-contrib/nginx-opentracing/tree/master/example/lua/jaeger

[cgilmour]

Hi @Lovivan I've put an example here for now, and the lua spans show up for me.
I might PR this, but not sure if there's an active maintainer on nginx-opentracing these days.