modify rd email (#43837)

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## Feature
- [X] Documentation added

SECURITY.md

@@ -4,6 +4,6 @@ If you believe you have found a security vulnerability in Next.js, we encourage
 
 We will investigate all legitimate reports and do our best to quickly fix the problem.
 
-Email `security@vercel.com` to disclose any security vulnerabilities.
+Email `responsible.disclosure@vercel.com` to disclose any security vulnerabilities.
 
 https://vercel.com/security