[10.0.0] Missing examples for 10.0.0 release

[domhanak]

As per discussion in ML: https://lists.apache.org/thread/qc9vhod96mdoppo5ssj4f0pkqhzt4ghd

Summary

Community users do not have example to use with 10.0.0 release. We should do something so they have
examples to work with.

Goal

Provide examples that work with 10.0.0 release.

Non-goal

Include them as part of release and publish their sources as part of the released stuff in Apache KIE
Solve the development and CI problem.

Solution

Create stable-10.0.0 branch from current 10.0.x where the 10.0.0 versions updates are done and all required work to make these work with release can proceed on this branch.

[domhanak]

I have created #2053 to highlight the issue on stable branch to our customers, while we resolve his issue.

[domhanak]

Infra issue to set main as default branch. - https://issues.apache.org/jira/browse/INFRA-26490

[domhanak]

Default branch is main now. Looks good.

Sent a PR to update website: apache/incubator-kie-website#17