Docs: Add SECURITY.md policy (for beginners)

[tyleruploads]

Goal

We want to add a SECURITY.md file to the root of our repository so people know how to report vulnerabilities privately.

Steps to Complete

1. Fork the repository
2. Create a file named SECURITY.md in the root of the repository's fork.
3. Copy and paste the text from the template below into the file.
4. Set the commit message to something like "Add SECURITY.md" and commit!
5. Submit a Pull Request that references this issue number.

SECURITY.md Template

# Security Policy
If you find a security issue or vulnerability, please do not open a public Issue or Pull Request.

Instead, please report it privately via one of these two methods:

1. Complete the [Google Form](https://forms.gle/tdzaSjcFaL4RwGPe9). Set the Inquiry Category to "Security Issue with a GitHub Repository of @tyleruploads", and start the inquiry with the name of this repository (devtkit).
2. Email me at [`tyleruploads@yahoo.com`](mailto:tyleruploads@yahoo.com).

### Note on Response Times
This is a small, solo project maintained by a middle school student in my spare time. Because of this, I may not be immediately available, and the issue may take some time to be resolved. There is a period of time in the year when I generally will not be able to be contacted, from near the end of June until around one month later. During that period, issues will not be addressed. Thank you for your patience and eagerness to improve the security of this project!