Create Local Network Contract Demo tutorial.

@hammertoe has created a video tutorial showing how to spin up a local network, and showcase the contract workflow. This issue tracks converting that video presentation into a text-based tutorial.

Video presentation is here: https://lvpr.tv/?v=5ae78luof6rv32vj

The steps in the presentation are:

1. Clone the FVM local-network repo.
1. Spin up Docker to create a local testnet.
1. Use Hardhat to deploy the DealClient contract to the local testnet.
1. Invoke the contract with details of what data you want to store.
1. View the storage deal in a local Boost instance.
1. Publish the storage deal.
1. Fetch data from the local testnet using Lassie.

@hammertoe will tech review this once its ready