Provide more mature roadmap

[tomkerkhove]

Provide more mature roadmap so we can better manage work and provide a better way of consuming the information for end-users to set expectations.

The new GitHub Projects will be used to bring our backlog to life.

Tasks

• [x] Set up a new GitHub Project
• [x] Automatically add new core issues to our roadmap
• [x] Document how work needs to be added to iterations
• [x] Document how end-users can consume our backlog
  • [x] Update our GitHub repo
  • [x] Update our docs

[tomkerkhove]

GitHub Project is available on https://github.com/orgs/kedacore/projects/2/views/1

[tomkerkhove]

Automatically add new core issues to our roadmap was done through https://github.com/kedacore/keda/pull/2622