message: check: update README.md
diff: It allows checking if the Wasm binary is a proper smart contract that's ready to
  be uploaded to the blockchain.
  -Installation:
  +## Installation
  ```sh
  cargo install cosmwasm-check
  ```
  +
  +## Usage
  +
  +Get help and info:
  +
  +```sh
  +cosmwasm-check -h
  +```
  +
  +Check some contracts:
  +
  +```sh
  +cosmwasm-check artifacts/hackatom.wasm artifacts/burner.wasm
  +```
  +
  +Check an entire directory of contracts (shell dependent):
  +
  +```sh
  +cosmwasm-check artifacts/*.wasm
  +```
  +
  +Check if a contract would ran on a blockchain with a specific set of
  +capabilities:
  +
  +```sh
  +cosmwasm-check --available-capabilities iterator,osmosis,friendship artifacts/hackatom.wasm
  +```
  +
  +## License
  +
  +This package is part of the cosmwasm repository, licensed under the Apache
  +License 2.0 (see [NOTICE](https://github.com/CosmWasm/cosmwasm/blob/main/NOTICE)
  +and [LICENSE](https://github.com/CosmWasm/cosmwasm/blob/main/LICENSE)).
  