admin-guide: clarify queue property name requirements

Problem: There is a statement in the admin guide that it is good
practice to use property names that match the corresponding queue
name, but no reason for this practice is given.

Explain that queue properties do not need to match the queue name,
but note that it is good practice because it allows flux-resource
list to suppress these duplicate names in is output.

Author: grondo

doc/guide/admin.rst

@@ -732,8 +732,12 @@ Adding Queues
 
 It may be useful to configure a Flux system instance with multiple queues.
 Each queue should be associated with a non-overlapping resource subset,
-identified by property name.  It is good practice for queues to create a
-new property that has the same name as the queue.
+identified by property name. It is good practice for queues to create a
+new property that has the same name as the queue. (There is no requirement
+that queue properties match the queue name, but this will cause extra entries
+in the PROPERTIES column for these queues. When queue names match property
+names, :command:`flux resource list` suppresses these matching properties
+in its output.)
 
 When queues are defined, all jobs must specify a queue at submission time.
 If that is inconvenient, then ``policy.jobspec.defaults.system.queue`` may