fix: update the pull request template (#717)

pkg/create-pr-new-pkg/pr_template.md

@@ -4,7 +4,8 @@
 
 - [ ] Read [CONTRIBUTING.md](https://aquaproj.github.io/docs/products/aqua-registry/contributing)
   - [ ] Read [OSS Contribution Guide](https://github.com/suzuki-shunsuke/oss-contribution-guide/blob/main/README.md)
-- [ ] [All commits are signed](https://docs.github.com/en/authentication/managing-commit-signature-verification/signing-commits)
+- [ ] [All commits are signed](https://github.com/suzuki-shunsuke/oss-contribution-guide/blob/main/docs/commit-signing.md)
+  - This repository enables `Require signed commits`, so all commits must be signed
 - [ ] [Avoid force push](https://github.com/suzuki-shunsuke/oss-contribution-guide?tab=readme-ov-file#dont-do-force-pushes-after-opening-pull-requests)
 - [ ] Do only one thing in one Pull Request
 - [ ] [Execute cmdx s to scaffold code](https://aquaproj.github.io/docs/products/aqua-registry/contributing/#use-cmdx-s-definitely)