Creating instructions to install the repository for the first time

Author: joaobrunoah

README.md

@@ -1,2 +1,5 @@
 # custom-pool-v3
+
 Example of external custom pool for Balancer V3. Extend it to create new pool types.
+
+forge install && yarn && cd lib/balancer-v3-monorepo && yarn && yarn build && cd ../.. && yarn build && yarn test:hardhat