Add Security Section to README.md (for beginners)

[tyleruploads]

Goal

We want to add a section to the README.md file that will direct people to our newly created SECURITY.md file to receive information on how to report security issues.

Steps to Complete

1. Fork the repository.
2. Open the file named README.md in the root of the repository's fork.
3. Copy and paste the section below under the Contributing section, but above the License section.
4. Set the commit message to something like "Add security section to README.md" and commit!
5. Submit a Pull Request that references this issue number.

Security Section Template

## Security
For information on reporting security vulnerabilities in devtkit, see [SECURITY.md](SECURITY.md)