Add comments to env.template

env.template

@@ -2,18 +2,27 @@
 
 SINGLE_USER_MODE=false
 
+# Note: Changing LOCAL_DOMAIN at a later time will cause unwanted side effects, including breaking all existing federation.
+# LOCAL_DOMAIN should *NOT* contain the protocol part of the domain e.g https://example.com.
 LOCAL_DOMAIN=
 
+# Use this only if you need to run mastodon on a different domain than the one used for federation.
+# You can read more about this option on https://github.com/tootsuite/documentation/blob/master/Running-Mastodon/Serving_a_different_domain.md
+WEB_DOMAIN=
+
+# Database configuration
 DB_HOST=
 DB_PORT=
 DB_NAME=
 DB_USER=
 DB_PASS=
 
+# Service dependencies
 REDIS_HOST=
 REDIS_PORT=
 REDIS_PASSWORD=
 
+# E-mail configuration
 SMTP_SERVER=
 SMTP_PORT=
 SMTP_FROM_ADDRESS=
@@ -22,6 +31,7 @@ SMTP_PASSWORD=
 SMTP_AUTH_METHOD=plain
 SMTP_OPENSSL_VERIFY_MODE=none
 
+# SSO configuration
 LDAP_ENABLED=
 LDAP_HOST=
 LDAP_PORT=
@@ -32,6 +42,10 @@ LDAP_UID=username
 LDAP_SEARCH_FILTER=(|(%{uid}=%{email})(mail=%{email}))
 LDAP_METHOD=plain
 
+# Application secrets
 SECRET_KEY_BASE=
 OTP_SECRET=
 
+# Optionally change default language
+# DEFAULT_LOCALE=de
+