This will pull the latest version of vertcoind and ElectrumX, start syncing the blockchain, generate an SSL certificate and start listening for secure Electrum traffic on port 55002.
All blockchain/vertcoind data will be stored in `./data/vertcoind` and all ElectrumX data will be stored in `./data/electrumx`. This is stored on the host machine and mounted in the docker container as a volume, meaning it will persist across reboots/updates/containers etc.
Yep, this is built to have sensible, safe defaults out of the box. vertcoind JSON-RPC is only accessible from the ElectrumX container, it's never exposed to the internet, it's not even exposed to localhost. ElectrumX will generate a fresh SSL certificate on first boot and only listen for SSL traffic. Unencrypted traffic will be ignored.