Update docs for `SafeERC20.forceApprove` (#4231)

contracts/token/ERC20/utils/SafeERC20.sol

@@ -70,8 +70,8 @@ library SafeERC20 {
 
     /**
      * @dev Set the calling contract's allowance toward `spender` to `value`. If `token` returns no value,
-     * non-reverting calls are assumed to be successful. Compatible with tokens that require the approval to be set to
+     * non-reverting calls are assumed to be successful. Meant to be used with tokens that require the approval
-     * 0 before setting it to a non-zero value.
+     * to be set to zero before setting it to a non-zero value, such as USDT.
      */
     function forceApprove(IERC20 token, address spender, uint256 value) internal {
         bytes memory approvalCall = abi.encodeCall(token.approve, (spender, value));