Update documentation for serverless-workflow-testing-with-rest-assured example

[LuboTerifaj]

Description

Update documentation for serverless-workflow-testing-with-rest-assured example.

Details

There is adoc reference in the readme file.
adoc file is not aimed to be used directly in the guidelines/readme file. It is just a source that may not be formatted properly.
In addition, the referenced guide is currently in kie repository instead of apache. See https://github.com/kiegroup/kogito-docs/blob/main/serverlessworkflow/modules/ROOT/pages/testing-and-troubleshooting/basic-integration-tests-with-restassured.adoc

Acceptance criteria

The readme file is updated as follows:

• The readme file should contain the guide that is readable and well formatted.
• The readme file format is one of the following:
  • A text directly embedded to the readme file.
  • The readme file can be referenced, but it must be accessible, and it is published in apache managed repository/sources.

Implementation ideas

No response