add test instruction in README

Author: adrianmcli

README.md

@@ -7,3 +7,5 @@ Demonstrates testing off a fork of Mainnet. More details here: https://studydefi
 After cloning and running `npm install`, you'll need a Mainnet node and a private key (any will do).
 
 You can get one from Infura or a pseudo-archive node from https://moonnet.now.sh/
+
+Run the tests with `npx jest`.