Automatic merge from submit-queue (batch tested with PRs 45724, 48051, 46444, 51056, 51605)
kubectl: Clean up documentation for rollout_status.go
**What this PR does / why we need it**:
`golint` emits various warnings about missing comments for exported funcitons and types.
This PR adds missing documentation strings to functions and types. Also adds punctuation to current documentation strings in line with Go coding standards.
**Release note**:
```release-note
NONE
```
/sig cli
/kind cleanup
/kind documentation