Explain how to develop che-dashboard with Eclipse Che

[dkwon17]

Is your task related to a problem? Please describe

There is now a devfile v2 for the che-dashboard repository: https://github.com/eclipse-che/che-dashboard/blob/main/devfile.yaml.

It would be great if there was a section in the che-dashboard README that explains how to develop dashboard with the devfile v2 on Eclipse Che / workspaces.openshift.com.

Describe the solution you'd like

Maybe a Contributing section, or a How to develop using Che section in the README would suffice.

It could cover:

• starting the workspace
• downloading dependencies and building with the tasks defined in the devfile
• pushing to remote, making a PR

Describe alternatives you've considered

An alternative could be a CONTRIBUTING.md file instead, which is linked in the README

Additional context

No response