Add a note about Stack Dep Ref triggering logic

Author: peterdeme

docs/concepts/stack/stack-dependencies.md

@@ -80,6 +80,10 @@ output "dummy" {
 !!! note
     If you are using CloudFormation - adding an output is considered a [no-op](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/troubleshooting.html#troubleshooting-errors-no-updates-to-perform){: rel="nofollow"}, so if you are making an output-only change, you will need to make a modification to the Resources section of the CloudFormation template that is recognized as a change by CF - e.g adding a dummy resource like `AWS::CloudFormation::WaitConditionHandle`.
 
+#### Reconciling failed runs
+
+When detecting changes in outputs, we also consider the previous run of the dependent stack. If the previous run wasn't successful, we'll trigger it regardless of the output changes. This is to ensure that the dependent stack has a chance to recover from a potential failure.
+
 #### Vendor limitations
 
 [Ansible](../../vendors/ansible/) and [Kubernetes](../../vendors/kubernetes/) does not have the concept of outputs, so you cannot reference the outputs of them. They _can_ be on the receiving end though: