Improve documentation

[isaachier]

Self-explanatory issue

[ringerc]

Would be good to have a quickstart example mentioning:

• A minimal explanation of how Jaeger relates to opentracing - you configure and init opentracing with a Jaeger backend then largely use the opentracing APIs thereafter, though possibly via the Jaeger wrappers and headers (?).
• How to init a Jaeger tracing singleton and set it up via the opentracing api with opentracing::Tracer::InitGlobal
• the YAML config support, with a link to the configuration docs;
• This example Ryan wrote Traces not showing up in jaeger. #14 (but note that it doesn't use the tracer singleton or anything)
• A reference to https://github.com/opentracing-contrib/nginx-opentracing/blob/master/jaeger/src/ngx_http_jaeger_module.cpp for a more real world example, with https://github.com/opentracing-contrib/nginx-opentracing/blob/master/opentracing/src/ngx_http_opentracing_module.cpp showing how the opentracing api gets used. Looks like https://github.com/opentracing-contrib/nginx-opentracing/blob/master/opentracing/src/opentracing_request_instrumentor.cpp#L75 is one of the key parts.

[ringerc]

@isaachier Wrote a draft for you. Code examples need checking, and I'm sure you can correct the bits I got wrong, but it should help. See above-linked commit.

[manannayak]

Thanks a lot of writing it up, Craig!

Btw - is there a plan to merge this into master?

[isaachier]

Unfortunately this isn't a pull request, it's an issue. Also, it is probably outdated at this point.

[yurishkuro]

Looks like the content is in a branch, that can be converted to a PR. Don't know about it being up to date.

[isaachier]

I think this was part of a much bigger P.R. I ultimately closed due to merge conflicts and no response from @ringerc (who is too busy to fix it at the moment). See #46.