+ me for Dutch (#5349)

I didn't received  the memo, but I just follow the flow.

CODEOWNERS

@@ -22,3 +22,11 @@
 /app/views/user_mailer/*.fr.text.erb @aldarone
 /config/locales/*.fr.yml @aldarone
 /config/locales/fr.yml @aldarone
+
+# Dutch
+/app/javascript/mastodon/locales/nl.json @jeroenpraat
+/app/javascript/mastodon/locales/whitelist_nl.json @jeroenpraat
+/app/views/user_mailer/*.nl.html.erb @jeroenpraat
+/app/views/user_mailer/*.nl.text.erb @jeroenpraat
+/config/locales/*.nl.yml @jeroenpraat
+/config/locales/nl.yml @jeroenpraat