kaspad/mining/simulator/docker

1. To build docker image invoke following command from btcd root directory:
    docker build -t mining_simulator -f ./mining/simulator/docker/Dockerfile .

2. To run:
    a. create folder ~/.btcd/mining_simulator with the following files:
        rpc.cert - certificate file that all rpc nodes accept
        addresses - list of node addresses in the format [hostname]:[port]. One node per line
    b. run:
         docker run -v ~/.btcd:/root/.btcd -t mining_simulator