docs: (PSKD-1500) update CONTRIBUTING.md with new expectations

CONTRIBUTING.md

@@ -6,14 +6,49 @@ We just ask that you follow our contribution guidelines when you do.
 Contributions to this project must be accompanied by a signed [Contributor Agreement](ContributorAgreement.txt).
 You (or your employer) retain the copyright to your contribution; this simply grants us permission to use and redistribute your contributions as part of the project.
 
-## Code reviews
-All submissions to this project—including submissions from project members—require review.
-Our review process typically involves performing unit tests, development tests, integration tests, and security scans using internal SAS infrastructure.
-For this reason, we don’t often merge pull requests directly from GitHub.
+## Code Reviews
+All submissions to this project—including submissions from project members—require
+review. Our review process typically involves performing unit tests, development
+tests, integration tests, and security scans.
 
-Instead, we work with submissions internally first, vetting them to ensure they meet our security and quality standards.
-We’ll do our best to work with contributors in public issues and pull requests; however, to ensure our code meets our internal compliance standards, we may need to incorporate your submission into a solution we push ourselves.
+## Pull Request Requirement
 
-This does not mean we don’t value or appreciate your contribution.
-We simply need to review your code internally before merging it.
-We work to ensure all contributors receive appropriate recognition for their contributions, at least by acknowledging them in our release notes.
+### Conventional Commits
+All pull requests must follow the [Conventional Commit](https://www.conventionalcommits.org/en/v1.0.0/)
+standard for commit messages. This helps maintain a consistent and meaningful
+commit history. Pull requests with commits that do not follow the Conventional
+Commit format will not be merged.
+
+### Developer Certificate of Origin Sign-Off
+This project requires all commits to be signed off in accordance with the [Developer Certificate of Origin (DCO)](https://developercertificate.org/).
+By signing off your commits, you certify that you have the right to submit the
+contribution under the open source license used by this project.
+
+To sign off your commits, use the --signoff flag with git commit:
+
+```bash
+git commit --signoff -m "Your commit message"
+```
+
+This will add a Signed-off-by line to your commit message, e.g.:
+
+```bash
+Signed-off-by: You Name <[email protected]>
+```
+
+For more information, please refer to https://probot.github.io/apps/dco/
+
+### Linter Analysis Checks
+All pull requests must pass our automated analysis checks before they can be
+merged. These checks include:
+
+- **Hadolint** – for Dockerfile best practices
+- **ShellCheck** – for shell script issues
+- **TFLint** – for Terraform code quality
+
+## Security Scans
+To ensure that all submissions meet our security and quality standards, we perform
+security scans using internal SAS infrastructure. Contributions might be subjected
+to security scans before they can be accepted. Reporting of any Common Vulnerabilities
+and Exposures (CVEs) that are detected is not available in this project at this
+time.