remove network from options passed to NodeClient and WalletClient

[pinheadmz]

This is kind of an amazing oversight, but NodeClient and WalletClient actually do no parse network as options. The command line utilities (like hsd-cli) do, but then the CLI program itself just parses that to determine which port setting to pass the actual client object.

All the JavaScript examples in the API docs can be updated to remove these from the options:

  network: network.type,

In addition, the line can be cleared out from the "Using Javascript Clients" section.

This change should be backported to bcoin docs as well: https://github.com/bcoin-org/bcoin-org.github.io