docs: reorganize topologyKey constraints

Signed-off-by: willise <[email protected]>

Author: willise

content/en/docs/concepts/configuration/assign-pod-node.md

@@ -226,10 +226,11 @@ The legal operators for pod affinity and anti-affinity are `In`, `NotIn`, `Exist
 In principle, the `topologyKey` can be any legal label-key. However,
 for performance and security reasons, there are some constraints on topologyKey:
 
-1. For affinity and for `requiredDuringSchedulingIgnoredDuringExecution` pod anti-affinity,
-empty `topologyKey` is not allowed.
-2. For `requiredDuringSchedulingIgnoredDuringExecution` pod anti-affinity, the admission controller `LimitPodHardAntiAffinityTopology` was introduced to limit `topologyKey` to `kubernetes.io/hostname`. If you want to make it available for custom topologies, you may modify the admission controller, or simply disable it.
-3. For `preferredDuringSchedulingIgnoredDuringExecution` pod anti-affinity, empty `topologyKey` is not allowed.
+1. For pod affinity, empty `topologyKey` is not allowed in both `requiredDuringSchedulingIgnoredDuringExecution`
+and `preferredDuringSchedulingIgnoredDuringExecution`.
+2. For pod anti-affinity, empty `topologyKey` is also not allowed in both `requiredDuringSchedulingIgnoredDuringExecution`
+and `preferredDuringSchedulingIgnoredDuringExecution`.
+3. For `requiredDuringSchedulingIgnoredDuringExecution` pod anti-affinity, the admission controller `LimitPodHardAntiAffinityTopology` was introduced to limit `topologyKey` to `kubernetes.io/hostname`. If you want to make it available for custom topologies, you may modify the admission controller, or simply disable it.
 4. Except for the above cases, the `topologyKey` can be any legal label-key.
 
 In addition to `labelSelector` and `topologyKey`, you can optionally specify a list `namespaces`