Update docs to document peer support in network status response

# Task context
- Peers list was added to `/network/status` response in v.1.3.2 release. We need to document the behavior, flag usage and API specs.

# Task checklist

- [ ] Document `PEER_DISCOVERY` flag in env vars page, with explanation of behaviors
- [ ] Document api docs for `/network/status` response
- [ ] Replace btc placeholders with Cardano examples (hosts, ports, network identifiers, etc)
- [ ] Add examples for peer list responses and typical values seen in preprod/mainnet
- [ ] Add specification for "minItems: 1" (this will be checked by schema verification)