Automatic merge from submit-queue (batch tested with PRs 63871, 63927, 63966, 63957, 63844). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add strategy description for 'kubectl describe sts' command

**What this PR does / why we need it**:
To display `UpdateStrategyType` and `RollingUpdateStrategy` information when execute `kubectl describe sts` command, the output likes:
```
Name:               web
Namespace:          default
CreationTimestamp:  Thu, 17 May 2018 10:21:19 +0800
Selector:           app=nginx
Labels:             app=nginx
Annotations:        <none>
Replicas:           3 desired | 1 total
Update Strategy:    RollingUpdate
  Partition:        2
Pods Status:        0 Running / 1 Waiting / 0 Succeeded / 0 Failed
Pod Template:
  Labels:  app=nginx
  Containers:
   nginx:
    Image:        k8s.gcr.io/nginx-slim:0.8
    Port:         80/TCP
    Host Port:    0/TCP
    Environment:  <none>
    Mounts:
      /usr/share/nginx/html from www (rw)
  Volumes:  <none>
Volume Claims:
  Name:          www
  StorageClass:  my-storage-class
  Labels:        <none>
  Annotations:   <none>
  Capacity:      1Gi
  Access Modes:  [ReadWriteOnce]
Events:
  Type    Reason            Age   From                    Message
  ----    ------            ----  ----                    -------
  Normal  SuccessfulCreate  10s   statefulset-controller  create Pod web-0 in StatefulSet web successful
```

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes None

**Special notes for your reviewer**:

**Release note**:

```release-note
Add 'UpdateStrategyType' and 'RollingUpdateStrategy' to 'kubectl describe sts' command output.
```