Reestructure README docs

[acuarica]

The current README sitting at the project's root folder contains mostly design decisions and implementation details. This is quite useful for contributors to help them understand the project. However, this is not the case for consumers/users of the Hardhat plugin and Foundry library.

Include the appropriate documentation targeting final users in this README. This should include basic instructions on how to use both solutions, and any configuration necessary to make it work. The PR¹ includes some documentation regarding the Foundry library.

One possible solution could be to structure the design docs as following²

• docs/README.md - general approach that we've laid out mostly on the README in terms of intercepting calls, system contracts, HTS tokens that support ERCs, etc.
• docs/storage.md - more details and structure to the storage methodology also laid out in the README.
• docs/hardhat-forking.md - the specific Hardhat approach. The sequence diagram in the README belongs here.
• docs/foundry-forking.md - the specific Foundry approach. Explain how we use the same base contract to reuse behavior and storage layout, but we provide the actual data from Mirror Node calls within the EVM¹.

If splitting up this design docs becomes problematic due to how interleaved both solutions are, we could have a single DESIGN.md sitting at the root folder containing all of it.

Footnotes

1. https://github.com/hashgraph/hedera-forking/pull/105 ↩ ↩²

2. Thanks @Nana-EC for the suggestion. ↩