Add security.txt to CODEOWNERS (#9006)

Add security.txt to CODEOWNERS for security team oversight.

Consequence of #9005

Signed-off-by: Brian Muenzenmeyer <brian.muenzenmeyer@gmail.com>

Author: bmuenzenmeyer

.github/CODEOWNERS

@@ -36,6 +36,7 @@ LICENSE @nodejs/tsc
 CONTRIBUTING.md @nodejs/nodejs-website @nodejs/web-infra
 docs @nodejs/nodejs-website @nodejs/web-infra
 SECURITY.md @nodejs/security-wg
+apps/site/public/.well-known/security.txt @nodejs/security-wg
 
 # Node.js Release Blog Posts
 apps/site/pages/en/blog/release @nodejs/releasers