docs: added .github/SECURITY.md

Author: JoshuaKGoldberg

.github/SECURITY.md

@@ -0,0 +1,9 @@
+# Security Policy
+
+We take all security vulnerabilities seriously.
+If you have a vulnerability or other security issues to disclose:
+
+-   Thank you very much, please do!
+-   Please send them to us by emailing `git@joshuakgoldberg.com`
+
+We appreciate your efforts and responsible disclosure and will make every effort to acknowledge your contributions.