Added Error Message

Added a descriptive error message to enhance clarity when errors are encountered.

apps/remix-ide/contracts/ballot.sol

@@ -60,7 +60,7 @@ contract Ballot {
             !voters[voter].voted,
             "The voter already voted."
         );
-        require(voters[voter].weight == 0);
+        require(voters[voter].weight == 0, "Voter already has the right to vote.");
         voters[voter].weight = 1;
     }
 
@@ -135,4 +135,4 @@ contract Ballot {
     {
         winnerName_ = proposals[winningProposal()].name;
     }
-}
+}