[SECVULN-1533] chore: Clarify iptables Provider interface docs (#19704)

chore: Clarify iptables Provider interface docs

Add docs clarifying constraints on use and return values.

sdk/iptables/iptables.go

@@ -78,8 +78,11 @@ type Provider interface {
 	// ApplyRules executes rules that have been added via AddRule.
 	// This operation is currently not atomic, and if there's an error applying rules,
 	// you may be left in a state where partial rules were applied.
+	// ApplyRules should not be called twice on the same instance in order to avoid
+	// duplicate rule application.
 	ApplyRules() error
-	// Rules returns the list of rules that have been added but not applied yet.
+	// Rules returns the list of rules that have been added (including those not yet
+	// applied).
 	Rules() []string
 }