Users Guide is outdated

The [Users Guide](https://github.com/eclipse-ee4j/jsonb-api/blob/master/docs/src/docs/user-guide.adoc) still refers to Json Binding 1.0.1. It would be nice if it could be updated to reflect current best practices and help new users better understand how to use the API. Thanks!

Start with docs/src/docs/user-guide.adoc and review its references to Json Binding 1.0.1 against the current API and best practices. Update the guide so it accurately explains current usage and is more helpful to new users.

Written by the indexing model from the issue text.