Add reference to an example with embedded execution in Java

[LuboTerifaj]

Add reference to an example with embedded execution in Java to https://sonataflow.org/serverlessworkflow/main/getting-started/java-embedded-workflows.html

Details

Currently, there is no any reference to any example. It may take too much time for the users to set-up the project properly to try the being described example.

Acceptance criteria

There is a reference to working example in the documentation.

[LuboTerifaj]

Hello @kaldesai, I cannot assign the task to you. Feel free to redistribute the issue as needed. cc @domhanak Thanks!