Initial version

[MiroDudik]

This is the continuation of PR #1.

The goal of this PR is to set up the governance along the following lines:

Fairlearn organization may consist of multiple projects, but it will start off with just a single project “Fairlearn”.

Roles: Project Maintainers, Steering Committee, Advisory Board

Project Maintainers:

• They decide everything about the project by consensus or another agreed upon mechanism within the project.
  If the consensus cannot be reached / or somebody among the maintainers feels slighted, they can appeal to Steering Committee

Steering Committee = subset of Maintainers with the "executive function":

• resolve appeals
• admit new projects
• administer the trademark
• decide on organizational governance

Advisory Board = domain experts that set aside some time to help with Fairlearn.

• The Advisory Board would be invited to the Steering Committee meetings, but only SC would have an executive power--AB would be effectively non-voting members.

Initial Maintainers: Roman, Richard, Michael, Miro, Adrin, Hilde
Initial Advisory Board: Hanna, Mehrnoosh, Alex, Ken
Initial Steering Committee: Miro, Hilde, Adrin, Roman

[MiroDudik]

@adrinjalali , @hildeweerts , @riedgar-ms , @mmadaio , @LisaIbanez : please approve if you're okay with this!