docs: update "Setup Hardhat" section

The command to clean the hardhat project will fail, as the `src` directory does not exist in the [FHE template repo](https://github.com/zama-ai/fhevm-hardhat-template).

There is no `src` directory; but there is a `contracts` directory.

Author: enitrat

docs/solidity-guides/getting-started/quick-start-tutorial/setup.md

@@ -143,5 +143,5 @@ cd <your-new-repo-name>
 Then run:
 
 ```sh
-rm -rf test/* src/* tasks/* deploy ./fhevmTemp ./artifacts ./cache ./coverage ./types ./coverage.json ./dist
+rm -rf test/* contracts/* tasks/* deploy ./fhevmTemp ./artifacts ./cache ./coverage ./types ./coverage.json ./dist
 ```