docs: update product-alerts.component.1.ts

[bradlygreen]

Make the example match the generated output seen in StackBlitz as shown https://next.angular.io/getting-started#input step 2 "Open product-alerts.component.ts."

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• angular.io application / infrastructure changes
• Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

• Yes
• No

Other information

[ngbot]

I see that you just added the PR action: merge label, but the following checks are still failing:
     status "ci/circleci: integration_test" is failing
     status "ci/circleci: test_aio" is failing
     missing required status "ci/circleci: publish_snapshot"

If you want your PR to be merged, it has to pass all the CI checks.

If you can't get the PR to a green state due to flakes or broken master, please try rebasing to master and/or restarting the CI job. If that fails and you believe that the issue is not due to your change, please contact the caretaker and ask for help.

[IgorMinar]

CI fails because of the trailing whitespace, please fix.

[googlebot]

We found a Contributor License Agreement for you (the sender of this pull request), but were unable to find agreements for all the commit author(s) or Co-authors. If you authored these, maybe you used a different email address in the git commits than was used to sign the CLA (login here to double check)? If these were authored by someone else, then they will need to sign a CLA as well, and confirm that they're okay with these being contributed to Google.
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[googlebot]

CLAs look good, thanks!

ℹ️ Googlers: Go here for more info.

[benlesh]

@bradlygreen Looks like you just need to squash your commits and this is good to go.

[benlesh]

Caretaker note: test_aio CI was failing because this was an edit via the GitHub UI... merging.

[angular-automatic-lock-bot]

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