Update docs

docs/modules/api/examples/utilities/Multicall.sol

@@ -0,0 +1,15 @@
+// contracts/Box.sol
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.20;
+
+import {Multicall} from "@openzeppelin/contracts/utils/Multicall.sol";
+
+contract Box is Multicall {
+    function foo() public {
+        // ...
+    }
+
+    function bar() public {
+        // ...
+    }
+}