update the nova host aggregates links

https://docs.openstack.org/nova/latest/admin/aggregates.html link failure,
From openstack U version, this link is not in the user directory. Currently, only the latest version has been changed.
You are advised to change all the links

Change-Id: Ic3b5a0ac7d832b162848b363396264ed0bfc4a25
(cherry picked from commit 210f529)

Author: renliang17

doc/source/admin/config-qos-min-bw.rst

@@ -53,7 +53,7 @@ Limitations
 * If you mix ports with and without bandwidth guarantees on the same physical
   interface then the ports without a guarantee may starve. Therefore mixing
   them is not recommended. Instead it is recommended to separate them by
-  :nova-doc:`Nova host aggregates <user/aggregates>`.
+  :nova-doc:`Nova host aggregates <admin/aggregates>`.
 
 * Changing the guarantee of a QoS policy (adding/deleting a
   ``minimum_bandwidth`` rule, or changing the ``min_kbps`` field of a