chore(docs): Update PR template with missing steps (#3156)

[Per discussion](#3143 (comment)) we should make sure that users don't miss workflow generation when creating a new folder. Moreover a missing CODEOWNERS step was added here as well.

Co-authored-by: Karl Weinmeister <[email protected]>

Author: rsamborski

.github/PULL_REQUEST_TEMPLATE.md

@@ -10,5 +10,7 @@ Note: Before submitting a pull request, please open an issue for discussion if y
 - [ ] **Lint** pass:   `npm run lint` (see [Style](https://github.com/GoogleCloudPlatform/nodejs-docs-samples/blob/main/CONTRIBUTING.md#style))
 - [ ] These samples need a new **API enabled** in testing projects to pass (let us know which ones)
 - [ ] These samples need a new/updated **env vars** in testing projects set to pass (let us know which ones)
+- [ ] This sample adds a new sample directory, and I updated the [CODEOWNERS file](https://github.com/GoogleCloudPlatform/nodejs-docs-samples/blob/main/CODEOWNERS) with the codeowners for this sample
+- [ ] This sample adds a new sample directory, and I created [GitHub Actions workflow](https://github.com/GoogleCloudPlatform/nodejs-docs-samples/blob/main/CONTRIBUTING.md#adding-new-samples) for this sample
 - [ ] This sample adds a new **Product API**, and I updated the [Blunderbuss issue/PR auto-assigner](https://github.com/GoogleCloudPlatform/nodejs-docs-samples/blob/main/.github/blunderbuss.yml) with the codeowners for this sample
-- [ ] Please **merge** this PR for me once it is approved
+- [ ] Please **merge** this PR for me once it is approved