Review, validate, and improve the "Getting Started" docs for java

[fhightower]

I'd like to improve the docs here: https://docs.threatconnect.com/en/latest/java/java_sdk.html#getting-started-with-java-sdk so that someone can easily and quickly go from nothing to a working example that uses the Java SDK.

This "Getting Started" guide should be a simple, well-detailed, complete guide to getting started. A good model is the python sdk: https://docs.threatconnect.com/en/latest/python/quick_start.html.

[fhightower]

@gregmarut-tc : When you have some time, could you take a look at the current getting started guide for the Java SDK and propose some updates to help users who aren't very familiar with maven?

I've dabbled with Java and was trying to get a working app, but I'm not sure how maven fits into the picture. The end goal is to have a simple guide first-time users can walk through to get a script working that uses the SDK.