feat: update readme

cd stellio

PORT=8080 DB_PORT=5432 SUFFIX="-1" docker compose -p first_broker  up

```

if you prefer using an .env file or you are a windows user you can use the .example.env file to set the variable instead.

if you are a windows user or prefer using an .env file you can use the .example.env file to set the variable instead.

by changing the variables you can easilly launch a second instance of a broker 

```

PORT=8081 DB_PORT=5433 SUFFIX="-2" docker compose -p second_broker  up

```

## CAVEAT with docker network (for non leaf brokers)

## CAVEAT with localhost and docker (for non leaf brokers)

An application running on a container will not be able to contact another container on http://localhost:$PORT

you may need to call http://container-name:$PORT instead or put the network mode to "host" in the docker-compose. 

 No newline at end of file

It may need to call http://container-name:$PORT instead.

Another solution is to put the network mode to "host" in the docker-compose, but it can lead to some port conflict if you have multiple instances