Add warning about use of delete (#3412)

contracts/utils/structs/EnumerableSet.sol

@@ -26,6 +26,14 @@ pragma solidity ^0.8.0;
  *
  * As of v3.3.0, sets of type `bytes32` (`Bytes32Set`), `address` (`AddressSet`)
  * and `uint256` (`UintSet`) are supported.
+ *
+ * [WARNING]
+ * ====
+ *  Trying to delete such a structure from storage will likely result in data corruption, rendering the structure unusable.
+ *  See https://github.com/ethereum/solidity/pull/11843[ethereum/solidity#11843] for more info.
+ *
+ *  In order to clean an EnumerableSet, you can either remove all elements one by one or create a fresh instance using an array of EnumerableSet.
+ * ====
  */
 library EnumerableSet {
     // To implement this library for multiple types with as little code