This adds a new section to the admin scheduler configuration
docs devoted to allocation ratios to call out the differences
between the override config options and the initial ratio
options, and how they interplay with the resource provider
inventory allocation ratio override that can be performed
via the placement REST API directly.
This moves the note about bug 1804125 into the new section
and also links to the docs from the initial allocation ratio
config option help text.
Part of blueprint initial-allocation-ratios
Related-Bug: #1804125
Change-Id: I7d8e822cd40dccaf5244e2cd95fa1af43fa9ed87