This borrows from the release note in change
I01f20f275bbd5451ace5c1e6f41ab38d488dae4e to document the
regression, introduced in Ocata, where allocation ratio settings
in the aggregate core/ram/disk filters are not honored because
of placement being used by the FilterScheduler.
While there is related work going on around this in
blueprint initial-allocation-ratios and
blueprint placement-aggregate-allocation-ratios, it is still
a limitation in the current code base and needs to be called
out in the docs.
Change-Id: Ifaf596a8572637f843f47daf5adce394b0365676
Related-Bug: #1804125