Add feature pack listing to the WF docs

Somewhere in the WF docs we should include a listing of the "WF" feature packs. Perhaps a sharable page included by the Galleon Provisioning and Bootable JAR pages.

There would need to be some sort of categorization. The primary category including wildfly, wildfly-ee and wildfly-preview, the FPs shipped from the main WF code base.  Then external FPs, separated into at least 2 buckets based on some kind of maturity concept. e.g. wildfly-datasources-galleon-pack is "mature" and regularly updated to align with WF whereas other FPs in wildfly-extras are less so.

Not sure where wildfly-cloud-galleon-pack fits; perhaps with the first 3.

https://wildfly.zulipchat.com/#narrow/stream/174184-wildfly-developers/topic/List.20of.20galleon.20packs