Current docs describe the behavior. However, after the engineering bug fix (linked), rhn-engineering-owalsh recommends to expand the content to be a bit more specific, such as giving an example of overriding the nodeSelector for an individual service.

NOTE: The engineering work is targeted for 18.0.4. However, since the doc request is considered an enhancement and not a bug fix, the target for any doc updates needs to be for a Feature Release (TBD by the writer together with the DFG based on capacity and priority).