Document federation (aka what upstream calls multi-tenant).

Engineering issue  https://issues.redhat.com/browse/OSSM-261

Federation Sync Up agenda/meeting notes  https://docs.google.com/document/d/1igvZUfhxzTlzVGxOS_K82ZUAGBLyFRebRDKutVV8GKc/edit#heading=h.62skogh92z4i

Upstream implementation https://docs.google.com/document/d/1yphsEMPePGUpx_hHLGhieDtBGzo_w763pgwrsfDSpX4/edit#heading=h.cxz2jxliash0

Maistra Federation (user stories) https://docs.google.com/document/d/1DKvZpLvCCbicUgGug8rxxYS2yFl-nmVMnlUVkRchqyw/edit#heading=h.z5wxqvd6vpag

Federation Design  https://docs.google.com/document/d/1VeOxT0sSHI0I7XyXVvhtaFq7U1A1r06b3YagXsfyVx0/edit#heading=h.cmhapcl50xm1

Federation MVP (working doc) https://docs.google.com/document/d/11E-O5SacHO9KiiKUR-jzEqsso3-2L6GJjvn_KhMDK8o/edit#heading=h.hiof50dwlglj