Add section in README for deployments

Readme.md

@@ -43,6 +43,43 @@ To reuse a previously deployed `Token` contract, define the environment variable
 The deployment script will use `contractAt` from Hardhat Ignition to retrieve the existing contract
 instead of deploying a new one.
 
+Deployment
+----------
+
+To deploy the marketplace you need to define `HARDHAT_NETWORK`:
+
+```bash
+HARDHAT_NETWORK=localhost npm run deploy
+```
+
+Or you can you `npx` directly:
+
+```bash
+npx hardhat ignition deploy ignition/modules/marketplace.js --network localhost
+```
+
+Hardhat uses [reconciliation](https://hardhat.org/ignition/docs/advanced/reconciliation) to recover  
+from errors or resume a previous deployment.
+In our case, we will likely redeploy a new contract every time, so we will need to
+[clear the previous deployment](https://hardhat.org/ignition/docs/guides/modifications#clearing-an-existing-deployment-with-reset):
+
+```bash
+HARDHAT_NETWORK=localhost npm run deploy-reset
+```
+
+Or you can you `npx` directly:
+
+```bash
+npx hardhat ignition deploy ignition/modules/marketplace.js --network localhost --reset
+```
+
+To reuse a previously deployed `Token` contract, define the environment variable `TOKEN_ADDRESS`.
+The deployment script will use `contractAt` from Hardhat Ignition to retrieve the existing contract
+instead of deploying a new one.
+
+The deployment files are kept under version control [as recommended by Hardhat](https://hardhat.org/ignition/docs/advanced/versioning),  
+except the build files, which are 18 MB.
+
 Running the prover
 ------------------