Document support for converging inclusive gateway

[koevskinikola]

The diverging inclusive gateway is added to Zeebe in https://github.com/camunda/zeebe/issues/10031 as an external contribution. Of course, all the Camunda Platform 8 need to be aligned and support the feature.

We need to document how users can use the converging Inclusive Gateway and how it behaves (in detail). We should also describe common pitfalls and special behaviors, for example, like the Camunda 7 docs.

The following documentation section needs to be updated: https://docs.camunda.io/docs/next/components/modeler/bpmn/inclusive-gateways/

Link to product hub:

• https://github.com/camunda/product-hub/issues/364