message: launchpad-ledger: Add demo instructions to README
diff: [![npm version](https://img.shields.io/npm/v/@cosmjs/launchpad-ledger.svg)](https://www.npmjs.com/package/@cosmjs/launchpad-ledger)
  +## Supported platforms
  +
  +We use the
  +[@ledgerhq/hw-transport-webusb](https://github.com/LedgerHQ/ledgerjs/tree/master/packages/hw-transport-webusb)
  +library to connect to Ledger devices from the browser via USB. You can check the
  +support status of this library
  +[here](https://github.com/LedgerHQ/ledgerjs/tree/master/packages/hw-transport-webusb#support-status).
  +
  +## Running the demo
  +
  +Build the package for web:
  +
  +```sh
  +yarn pack-web
  +```
  +
  +Host the `launchpad-ledger` package directory, for example using Python 3:
  +
  +```sh
  +python3 -m http.server
  +```
  +
  +Visit the demo page in a browser, for example if using the Python 3 option:
  +[http://localhost:8000/demo]().
  +
  +Then follow the instructions on that page.
  +
  ## License
  This package is part of the cosmjs repository, licensed under the Apache License
  