Update servicebus_subscription_rule.html.markdown (#4051)

The import example for the subscription filter is incorrect- the resource type is 'azurerm_servicebus_subscription', where it should be 'azurerm_servicebus_subscription_rule'

Author: Singley

website/docs/r/servicebus_subscription_rule.html.markdown

@@ -160,5 +160,5 @@ The following attributes are exported:
 Service Bus Subscription Rule can be imported using the `resource id`, e.g.
 
 ```shell
-terraform import azurerm_servicebus_subscription.test /subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/mygroup1/providers/microsoft.servicebus/namespaces/sbns1/topics/sntopic1/subscriptions/sbsub1/rules/sbrule1
+terraform import azurerm_servicebus_subscription_rule.test /subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/mygroup1/providers/microsoft.servicebus/namespaces/sbns1/topics/sntopic1/subscriptions/sbsub1/rules/sbrule1
 ```