This changes does two things to the admin scheduler configuration
docs:
1. Notes the limitation from bug 1802111 for the older
AggregateMultiTenancyIsolation filter and mentions that
starting in Rocky, using tenant isolation with placement
is better.
2. Notes that when isolating tenants via placement, the metadata
key "filter_tenant_id" can be suffixed to overcome the limitation
in bug 1802111.
Change-Id: I792c5df01b7cbc46c8363e261bc7422b09180e56
Closes-Bug: #1802111