fix(server/flash): Api to match documentation

This fixes duplication issues and normalize our use with everyone else

server/middlewares/flash-cheaters.js

@@ -16,13 +16,14 @@ export default function flashCheaters() {
       EXCLUDED_PATHS.indexOf(req.path) === -1 &&
       req.user && req.url !== '/' && req.user.isCheater
     ) {
-      req.flash('danger', {
-        msg: dedent`
+      req.flash(
+        'danger',
+        dedent`
           Upon review, this account has been flagged for academic
           dishonesty. If you’re the owner of this account contact
           team@freecodecamp.org for details.
         `
-      });
+      );
     }
     return next();
   };