Updated Deployment concept docs (#6494)

* Updated Deployment concept docs

* Addressed comments

docs/concepts/workloads/controllers/deployment.md

@@ -296,7 +296,7 @@ It is generally discouraged to make label selector updates and it is suggested t
 In any case, if you need to perform a label selector update, exercise great caution and make sure you have grasped
 all of the implications.
 
-**Note:** In API version `apps/v1beta2`, a Deployment's label selector is immutable after it gets created.
+**Note:** In API version `apps/v1`, a Deployment's label selector is immutable after it gets created.
 {: .note}
 
 * Selector additions require the pod template labels in the Deployment spec to be updated with the new label too,
@@ -863,7 +863,7 @@ for the Pods targeted by this deployment.
 
 `.spec.selector` must match `.spec.template.metadata.labels`, or it will be rejected by the API.
 
-In API version `apps/v1beta2`, `.spec.selector` and `.metadata.labels` no longer default to `.spec.template.metadata.labels` if not set. So they must be set explicitly. Also note that `.spec.selector` is immutable after creation of the Deployment in `apps/v1beta2`.
+In API version `apps/v1`, `.spec.selector` and `.metadata.labels` do not default to `.spec.template.metadata.labels` if not set. So they must be set explicitly. Also note that `.spec.selector` is immutable after creation of the Deployment in `apps/v1`.
 
 A Deployment may terminate Pods whose labels match the selector if their template is different
 from `.spec.template` or if the total number of such Pods exceeds `.spec.replicas`. It brings up new
@@ -937,7 +937,7 @@ a Pod is considered ready, see [Container Probes](/docs/concepts/workloads/pods/
 
 ### Rollback To
 
-Field `.spec.rollbackTo` has been deprecated in API versions `extensions/v1beta1` and `apps/v1beta1`, and is no longer supported in API version `apps/v1beta2`. Instead, `kubectl rollout undo` as introduced in [Rolling Back to a Previous Revision](#rolling-back-to-a-previous-revision) should be used.
+Field `.spec.rollbackTo` has been deprecated in API versions `extensions/v1beta1` and `apps/v1beta1`, and is no longer supported in API versions starting `apps/v1beta2`. Instead, `kubectl rollout undo` as introduced in [Rolling Back to a Previous Revision](#rolling-back-to-a-previous-revision) should be used.
 
 ### Revision History Limit
 

docs/concepts/workloads/controllers/nginx-deployment.yaml

@@ -1,4 +1,4 @@
-apiVersion: apps/v1beta2 # for versions before 1.8.0 use apps/v1beta1
+apiVersion: apps/v1 # for versions before 1.9.0 use apps/v1beta2
 kind: Deployment
 metadata:
   name: nginx-deployment