Merge pull request #71305 from JoeAldinger/OSDOCS-8707

/lgtm OSDOCS-8707: clarification for external gateway

Author: JoeAldinger

modules/nw-secondary-ext-gw-about.adoc

@@ -6,7 +6,11 @@
 [id="nw-secondary-ext-gw-about_{context}"]
 = How {product-title} determines the external gateway IP address
 
-You configure a secondary external gateway with the `AdminPolicyBasedExternalRoute` custom resource from the the `k8s.ovn.org` API group. The custom resource (CR) supports static and dynamic approaches to specifying an external gateway's IP address. Each namespace that a `AdminPolicyBasedExternalRoute` CR targets cannot be selected by any other `AdminPolicyBasedExternalRoute` CR. A namespace cannot have concurrent secondary external gateways.
+You configure a secondary external gateway with the `AdminPolicyBasedExternalRoute` custom resource (CR) from the the `k8s.ovn.org` API group. The CR supports static and dynamic approaches to specifying an external gateway's IP address.
+
+Each namespace that a `AdminPolicyBasedExternalRoute` CR targets cannot be selected by any other `AdminPolicyBasedExternalRoute` CR. A namespace cannot have concurrent secondary external gateways.
+
+Changes to policies are isolated in the controller. If a policy fails to apply, changes to other policies do not trigger a retry of other policies. Policies are only re-evaluated, applying any differences that might have occurred by the change, when updates to the policy itself or related objects to the policy such as target namespaces, pod gateways, or namespaces hosting them from dynamic hops are made.
 
 Static assignment:: You specify an IP address directly.
 Dynamic assignment:: You specify an IP address indirectly, with namespace and pod selectors, and an optional network attachment definition.

modules/nw-secondary-ext-gw-object.adoc

@@ -32,7 +32,7 @@ from:
       kubernetes.io/metadata.name: novxlan-externalgw-ecmp-4059
 ----
 
-A namespace can be targeted by only one `AdminPolicyBasedExternalRoute` CR. If a namespace is selected by more than one `AdminPolicyBasedExternalRoute` CR, a `failed` error status occurs on the second and subsequent CRs targeting the same namespace.
+A namespace can only be targeted by one `AdminPolicyBasedExternalRoute` CR. If a namespace is selected by more than one `AdminPolicyBasedExternalRoute` CR, a `failed` error status occurs on the second and subsequent CRs that target the same namespace. To apply updates, you must change the policy itself or related objects to the policy such as target namespaces, pod gateways, or namespaces hosting them from dynamic hops in order for the policy to be re-evaluated and your changes to be applied.
 
 |`spec.nextHops`
 |`object`