Add SECURITY.md File

This just adds a copy of the Meta default SECURITY.md that we can then modify.

SECURITY.md

@@ -0,0 +1,7 @@
+# Reporting and Fixing Security Issues
+
+Please do not open GitHub issues or pull requests - this makes the problem immediately visible to everyone, including malicious actors. Security issues in this open source project can be safely reported via the Meta Bug Bounty program:
+
+https://www.facebook.com/whitehat
+
+Meta's security team will triage your report and determine whether or not is it eligible for a bounty under our program.