Generate artifacts from subdirectories

[jodator]

While #15 I've stumbled upon a problem with hardhat generated *.json files stored in nested directories.

[jodator]

I see two options here:

1. Scan directory provided with --input option recursively.
2. Support glob patterns in --inptu.

[nezouse]

Any update on that? Docs just redirect to hardhat website:

Before all, you need to compile contracts (here’s how it’s done with Waffle, Truffle, Hardhat) This will generate JSON files with contract ABIs. Usually they can be found under ./build directory.

But it's not working with default hardhat config which can be really troublesome for new users.