Add optional configuration section

Add details about consumer replicas

Add CONSUMER_REPLICAS to .env.example

Change `consumer: deploy: replicas` to use CONSUMER_REPLICAS var to keep user config options in one file

deployment/docker/.env.example

@@ -26,6 +26,7 @@ JOBS_ENABLED=true
 MAX_SINGLE_TORRENT_CONNECTIONS=10
 TORRENT_TIMEOUT=30000
 UDP_TRACKERS_ENABLED=true
+CONSUMER_REPLICAS=3
 
 # Producer
 RabbitMqConfiguration__Host=rabbitmq