docs: add security.md (#1759)

Co-authored-by: Josh Black <joshblack@users.noreply.github.com>
Co-authored-by: Jon Rohan <rohan@github.com>

.github/security.md

@@ -0,0 +1,31 @@
+Thanks for helping make GitHub safe for everyone.
+
+## Security
+
+GitHub takes the security of our software products and services seriously, including all of the open source code repositories managed through our GitHub organizations, such as [GitHub](https://github.com/GitHub).
+
+Even though [open source repositories are outside of the scope of our bug bounty program](https://bounty.github.com/index.html#scope) and therefore not eligible for bounty rewards, we will ensure that your finding gets passed along to the appropriate maintainers for remediation.
+
+## Reporting Security Issues
+
+If you believe you have found a security vulnerability in any GitHub-owned repository, please report it to us through coordinated disclosure.
+
+**Please do not report security vulnerabilities through public GitHub issues, discussions, or pull requests.**
+
+Instead, please send an email to opensource-security[@]github.com.
+
+Please include as much of the information listed below as you can to help us better understand and resolve the issue:
+
+- The type of issue (e.g., buffer overflow, SQL injection, or cross-site scripting)
+- Full paths of source file(s) related to the manifestation of the issue
+- The location of the affected source code (tag/branch/commit or direct URL)
+- Any special configuration required to reproduce the issue
+- Step-by-step instructions to reproduce the issue
+- Proof-of-concept or exploit code (if possible)
+- Impact of the issue, including how an attacker might exploit the issue
+
+This information will help us triage your report more quickly.
+
+## Policy
+
+See [GitHub's Safe Harbor Policy](https://docs.github.com/en/github/site-policy/github-bug-bounty-program-legal-safe-harbor#1-safe-harbor-terms)