Add missing double quotes

.env.example

@@ -32,7 +32,7 @@ MAIL_PORT=2525
 MAIL_USERNAME=null
 MAIL_PASSWORD=null
 MAIL_ENCRYPTION=null
-MAIL_FROM_ADDRESS="pixelfed@example.com
+MAIL_FROM_ADDRESS="pixelfed@example.com"
 MAIL_FROM_NAME="Pixelfed"
 
 SESSION_DOMAIN="${APP_DOMAIN}"