Maybe add how to set `server.root` to example?

[rud]

At this location:

https://github.com/rollbar/rollbar-java/blob/3197d2e059f4c692fc34c1687d663be18fb2561a/examples/rollbar-java/src/main/java/com/rollbar/example/Application.java#L37

Maybe add something like:

.server(() -> new Server.Builder().root("com.rollbar").build())

That way it should becomes possible to use source code linking. It took some digging to figure this out, the coding pattern didn't click, and I couldn't find any applicable documentation.

For a stronger example it might be an idea to move this example code to a different namespace, like "com.example.rollbar", but that's just a side-suggestion.