Use allow/deny-list instead of white/black-list in .env.production.sample

.env.production.sample has been nuked upstream, but we decided to keep it,
so change it to reflect latest changes in environment variable names.

(The link still refers to “whitelist_mode” because the documentation hasn't
been updated yet)

.env.production.sample

@@ -52,9 +52,9 @@ VAPID_PUBLIC_KEY=
 # Single user mode will disable registrations and redirect frontpage to the first profile
 # SINGLE_USER_MODE=true
 # Prevent registrations with following e-mail domains
-# EMAIL_DOMAIN_BLACKLIST=example1.com|example2.de|etc
+# EMAIL_DOMAIN_DENYLIST=example1.com|example2.de|etc
 # Only allow registrations with the following e-mail domains
-# EMAIL_DOMAIN_WHITELIST=example1.com|example2.de|etc
+# EMAIL_DOMAIN_ALLOWLIST=example1.com|example2.de|etc
 
 # Optionally change default language
 # DEFAULT_LOCALE=de
@@ -286,7 +286,7 @@ STREAMING_CLUSTER_NUM=1
 # https://docs.joinmastodon.org/admin/config/#authorized_fetch
 # AUTHORIZED_FETCH=true
 
-# Whitelist mode (optional)
-# Only allow federation with whitelisted domains, see
+# Limited federation mode (optional)
+# Only allow federation with specific domains, see
 # https://docs.joinmastodon.org/admin/config/#whitelist_mode
-# WHITELIST_MODE=true
+# LIMITED_FEDERATION_MODE=true