Feature Description

• One-line feature description (can be used as a release note): Role-based access control
• Primary contact (assignee): @ericchiang @deads2k @liggitt
• Responsible SIGs: sig-auth
• Design proposal link (community repo):
• Reviewer(s): @deads2k @ericchiang
• Approver (likely from SIG/area to which feature belongs): @erictune @smarterclayton
• Feature target (which target equals to which milestone):
  • Alpha release target - 1.3
  • Beta release target - 1.6
  • Stable release target - 1.8

kubernetes/kubernetes#25634
kubernetes/kubernetes#26753
kubernetes/website#643