It was pointed out [1] that the semantic difference between how the
`resources` query parameter is handled by GET /resource_providers versus
GET /allocation_candidates is not clear based on the API reference
descriptions, which are identical. This change set clarifies the
wording for both, making it clear that a) allocations are taking into
account; and b) GET /allocation_candidates is working with groups of
providers that must *collectively* satisfy the resource specification.
[1] https://review.openstack.org/#/c/547056/2/specs/rocky/approved/traits-on-list-resource-providers.rst@33
Change-Id: Ia2a4f8f80ec68dd9c95e084c292a2fe2d6ec1b2d