docs: add marketing team as code owners for partners and branding pages

Author: bjohansebas

.github/CODEOWNERS

@@ -48,3 +48,5 @@ apps/site/pages/en/learn/getting-started/security-best-practices.md @nodejs/secu
 apps/site/pages/en/learn/manipulating-files @nodejs/fs
 apps/site/pages/en/learn/test-runner @nodejs/test_runner
 apps/site/pages/en/learn/typescript @nodejs/typescript
+apps/site/pages/en/about/partners.md @nodejs/marketing
+apps/site/pages/en/about/branding.md @nodejs/marketing