Add "Supportability/Compatibility Notes" chapter in Release Notes

I'd like to request to add "Supportability/Compatibility Notes" chapter in Release Notes

The chapter would include:

1. Unsupported usages which were supported in previous versions:

• Serialization of kbase/package is not supported since version 6. See details in https://access.redhat.com/solutions/3216951

2. Important compatibility changes

• Property Reactivity is "ALWAYS" by default ("ALLOWED" in BRMS 6)

3. Removed features from previous versions:

• RETEOO engine has been removed

4. Deprecated features (if any)

This kind of information is spread across docs and may be overlooked. Aggregating to this chapter would be beneficial to all users and RH employees to avoid pitfalls (e.g. implemented an application with unsupported usages and then notice an issue long time later).

Also it would be important to ask our engineering team to provide information to this chapter before release.