Update SECURITY.md

SECURITY.md

 # Reporting Security Issues
 
-If you discover a security issue in Misskey, please report it by sending an
-email to [syuilotan@yahoo.co.jp](mailto:syuilotan@yahoo.co.jp).
+If you discover a security issue in Sharkey, please report it by sending an
+email to [admin@transfem.org](mailto:admin@transfem.org).
 
 This will allow us to assess the risk, and make a fix available before we add a
 bug report to the GitHub repository.
 
-Thanks for helping make Misskey safe for everyone.
+Thanks for helping make Sharke safe for everyone.