Update README.md

Author: six-days

README.md

@@ -2,4 +2,5 @@
 useful common ethereum contract repository
 
 - [Upgradeability Evidence Contract](https://github.com/six-days/ethereum-contracts/tree/master/evidence)
-- [Oracle & Query Demo Contract](https://github.com/six-days/ethereum-contracts/tree/master/oracle)
+- [Oracle & Query Demo Contract](https://github.com/six-days/ethereum-contracts/tree/master/oracle)
+- [ERC20 Token Lock](https://github.com/six-days/ethereum-contracts/tree/master/token)