text: Title: Pods with Shutdown status confuse users of graceful node shutdown feature
  Body: #### What happened:
  
  When using Graceful Node Shutdown feature, status and reason of "shutdown" pod  are confusing for users. See https://github.com/kubernetes/website/pull/28235/ where I attempt to address this confusion by documenting the behavior.
  
  However, it would be great to improve messages. Perhaps the following renaming:
  
  ```
  Status:         Failed. --------------------------------> Same
  Reason:         Shutdown ----------------------------> Terminated 
  Message:        Node is shutting, evicting pods ------> Pod was terminated in response to node shutdown.
  ```
  
  Reason "Shutdown" is confusing because it may appear as a process of shutting down. Better message will also be useful.
  
  #### What you expected to happen:
  
  Reason and Message changed for pods terminated in response to Node shutdown.
  
  #### How to reproduce it (as minimally and precisely as possible):
  
  Shutdown the node and observer the pod status.
  
  #### Anything else we need to know?:
  
  KEP: kubernetes/enhancements#2000
  /cc @bobbypage
  /sig node
  /help
  /good-first-issue
  
  #### Environment:
  - Kubernetes version (use `kubectl version`): 1.19+ (with feature enabled)
  