update apps/v1 types.go comments for controller spec selector fields

[crimsonfaith91]

What this PR does / why we need it:
This PR updates apps/v1 types.go comments (including removal of optional tag) for controller spec selector fields.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
xref #50808

Release note:

NONE

[janetkuo]

/lgtm

[crimsonfaith91]

/assign @smarterclayton
Required your approval for controller spec selector field comment change.

[k8s-github-robot]

[MILESTONENOTIFIER] Milestone Pull Request Current

@crimsonfaith91 @janetkuo @smarterclayton

Pull Request Labels

• sig/apps: Pull Request will be escalated to these SIGs if needed.
• priority/important-soon: Escalate to the pull request owners and SIG owner; move out of milestone after several unsuccessful escalation attempts.
• kind/bug: Fixes a bug discovered during the current release.

Help

• Additional instructions
• Commands for setting labels

[smarterclayton]

/approve

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: crimsonfaith91, janetkuo, smarterclayton

Associated issue: 50808

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these OWNERS Files:

• api/OWNERS [smarterclayton]
• docs/api-reference/OWNERS [smarterclayton]
• staging/src/k8s.io/api/OWNERS [smarterclayton]

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[k8s-github-robot]

/test all [submit-queue is verifying that this PR is safe to merge]

[k8s-github-robot]

Automatic merge from submit-queue. If you want to cherry-pick this change to another branch, please follow the instructions here.