Currently the `getnetworkinfo` returns something like: 

```
"localservices": "0000000000000449",
```

Manually parsing this consistently gives me a headache (see also https://github.com/sipa/bitcoin-seeder/pull/77).

It would be useful to parse this and show the right combination of `NODE_NETWORK`, `NODE_GETUTXO`, `NODE_BLOOM`, `NODE_WITNESS`, `NODE_NETWORK_LIMITED` and `NODE_COMPACT_FILTERS`. In addition the help text for `getnetworkinfo` could be expanded to mention the right BIP numbers for known flags.

There is some ad hoc parsing to populate e.g. `localrelay`, etc (?).  Their help text could also refer back to `NODE_GETUTXO`.

See also: https://en.bitcoin.it/wiki/Protocol_documentation#Network_address
: m_name{std::move(name)},
      m_description{std::move(description)},
      m_args{std::move(args)},
      m_results{std::move(results)},
      m_examples{std::move(examples)}
{
    std::set<std::string> named_args;
    for (const auto& arg : m_args) {
        
        assert(named_args.insert(arg.m_name).second);
    }
}
std::string RPCResults::ToDescriptionString() const
{
    std::string result;
    for (const auto& r : m_results) {
        if (r.m_cond.empty()) {
            result += "\nResult:\n";
        } else {
            result += "\nResult (" + r.m_cond + "):\n";
        }
        result += r.m_result;
    }
    return result;
}
std::string RPCExamples::ToDescriptionString() const