Improve http sender TLS documentation

[jaredallmond]

Requirement - what kind of business use case are you trying to solve?

Need to send Jaeger spans from an AWS Lambda node function to Jaeger Collector via TLS protected channel.

Problem - what in Jaeger blocks you from solving the requirement?

After reviewing docs and code it is unclear if TLS is completely supported, and if so how to manage certificate key pairs when configuring an http sender. Have reviewed jaegertracing/jaeger#1718 and jaegertracing/jaeger#2249 and it appears TLS is not currently supported. However in the jaeger-client-node I see a test was written for HTTPS https://github.com/jaegertracing/jaeger-client-node/blob/master/test/http_sender.js.

The current state of TLS support from node client to Collector is confusing.

Proposal - what do you suggest to solve the problem or improve the existing situation?

Clarify feature support, and if enabled please improve documentation with example of how to configure a TLS protected HTTPS sender node client.

Any open questions to address