remove redundant line in timelock contract

Author: AgeManning

README.md

@@ -296,7 +296,6 @@ contract TimeLock {
     function withdraw() public {
         require(balances[msg.sender] > 0);
         require(now > lockTime[msg.sender]);
-        uint balance = balances[msg.sender];
         uint transferValue = balances[msg.sender];
         balances[msg.sender] = 0;
         msg.sender.transfer(transferValue);