Improve docs on NATS Streaming

[bjflanne]

Examples

-The relationship between NATS Streaming and NATS Server - esp operationally WRT to if somebody is already running NATS Server what should they do.

-How to create a connection - some users eventually figured out you have to create a plain NATS connection first, but still are not sure they are doing it the best/simplest way.

[tylertreat]

I think this is also somewhat related to https://github.com/nats-io/go-nats-streaming/issues/152

[ColinSullivan1]

See also: nats-io/stan.java#62, #217

[rybit]

Some things that would also be really helpful

• an example of converting an existing connection to a streaming connection
• an example of how to configure and setup the streaming server (esp with AWS or the likes)
• the differences in the subscription starter points
• clarification with how long messages are persisted/addressable
• stats about throughput

Most of the information I have had to find by digging into the clients and the examples. That is less than ideal.

[ColinSullivan1]

@rybit , great feedback, much appreciated. This list is helpful.