Update docs

contracts/token/ERC6909/extensions/draft-ERC6909ContentURI.sol

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+// SPDX-License-Identifier: MIT
+// OpenZeppelin Contracts (last updated v5.3.0) (token/ERC6909/extensions/draft-ERC6909ContentURI.sol)
+
+pragma solidity ^0.8.20;
+
+import {ERC6909} from "../draft-ERC6909.sol";
+import {IERC6909ContentURI} from "../../../interfaces/draft-IERC6909.sol";
+
+/**
+ * @dev Implementation of the Content URI extension defined in ERC6909.
+ */
+contract ERC6909ContentURI is ERC6909, IERC6909ContentURI {
+    string private _contractURI;
+    mapping(uint256 id => string) private _tokenURIs;
+
+    /// @dev Event emitted when the contract URI is changed. See https://eips.ethereum.org/EIPS/eip-7572[ERC-7572] for details.
+    event ContractURIUpdated();
+
+    /// @dev See {IERC1155-URI}
+    event URI(string value, uint256 indexed id);
+
+    /// @inheritdoc IERC6909ContentURI
+    function contractURI() public view virtual override returns (string memory) {
+        return _contractURI;
+    }
+
+    /// @inheritdoc IERC6909ContentURI
+    function tokenURI(uint256 id) public view virtual override returns (string memory) {
+        return _tokenURIs[id];
+    }
+
+    /**
+     * @dev Sets the {contractURI} for the contract.
+     *
+     * Emits a {ContractURIUpdated} event.
+     */
+    function _setContractURI(string memory newContractURI) internal virtual {
+        _contractURI = newContractURI;
+
+        emit ContractURIUpdated();
+    }
+
+    /**
+     * @dev Sets the {tokenURI} for a given token of type `id`.
+     *
+     * Emits a {URI} event.
+     */
+    function _setTokenURI(uint256 id, string memory newTokenURI) internal virtual {
+        _tokenURIs[id] = newTokenURI;
+
+        emit URI(newTokenURI, id);
+    }
+}