Add README

README.md

@@ -2,6 +2,45 @@
 
 Disclaimer: this is a part of Penerbangan Pertama educational content, DO NOT USE ON PRODUCTION as this project contains intentional bug.
 
+IDRCoin is a implementation of ERC20 with custom logic.
+This coin is fixed stable coin, first in the world.
+But we do not guarantee the stability of the coin on DEX. We are not responsible for any loss.
+
+Use case of our token is, you can use it to gain access to our service, BankHub.
+IDRCoin can also be used for P2P on our platform later (not implemented yet).
+
+Anyone can have IDRCoin by trading it with USDT on `IDRCoin` contract.
+
+## BankHub
+
+BankHub is a platform that allows you to manage your finance.
+You can deposit your IDRCoin to BankHub by providing Bank address and gain interest.
+
+For now our official partner is Bank ABC and Bank IRB.
+
+But anyone can create their own bank and join our platform by providing KYC to us.
+
+## Scope
+
+```tree
+src/IDRCoin.sol
+src/BankHub.sol
+```
+
+## Out of Scope
+
+1. ALL interaction with DEX is out of scope in this audit.
+2. Currently there are no user withdrawal function in `IDRCoin` contract. So user can only bought IDRCoin with USDT, but cannot sell it back to USDT.
+
+## Known Issue
+
+`IDRCoin::conversionRate` is fixed at 16000.
+
+## Actors and Roles
+
+1. OWNER is trusted. All OWNER action is assumed to be correct. Issue related to OWNER action is invalid.
+2. BANK is the one who approved by OWNER to be a bank. BANK is the one who hold IDRCoin and provide interest to USER.
+3. USER is the one who interact with IDRCoin.
 
 ## Usage