add Available since 4.1 comments

contracts/access/AccessControl.sol

@@ -99,6 +99,8 @@ abstract contract AccessControl is Context, IAccessControl, ERC165 {
      * The format of the revert reason is given by the following regular expression:
      *
      *  /^AccessControl: account (0x[0-9a-f]{20}) is missing role (0x[0-9a-f]{32})$/
+     *
+     * _Available since v4.1._
      */
     modifier onlyRole(bytes32 role) {
         _checkRole(role, _msgSender());

contracts/interfaces/IERC1271.sol

@@ -5,6 +5,8 @@ pragma solidity ^0.8.0;
 /**
  * @dev Interface of the ERC1271 standard signature validation method for
  * contracts as defined in https://eips.ethereum.org/EIPS/eip-1271[ERC-1271].
+ *
+ * _Available since v4.1._
  */
 interface IERC1271 {
   /**

contracts/interfaces/IERC3156.sol

@@ -5,6 +5,8 @@ pragma solidity ^0.8.0;
 /**
  * @dev Interface of the ERC3156 FlashBorrower, as defined in
  * https://eips.ethereum.org/EIPS/eip-3156[ERC-3156].
+ *
+ * _Available since v4.1._
  */
 interface IERC3156FlashBorrower {
     /**

contracts/proxy/ERC1967/ERC1967Storage.sol

@@ -9,6 +9,8 @@ import "../../utils/StorageSlot.sol";
 /**
  * @dev This abstract contract provides setters and getters for the different
  * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] storage slots.
+ *
+ * _Available since v4.1._
  */
 abstract contract ERC1967Storage {
     /**

contracts/proxy/ERC1967/ERC1967Upgrade.sol

@@ -8,6 +8,8 @@ import "./ERC1967Storage.sol";
  * @dev This abstract contract provides event emitting update functions for
  * https://eips.ethereum.org/EIPS/eip-1967[EIP1967] slots.
  *
+ * _Available since v4.1._
+ *
  * @custom:oz-upgrades-unsafe-allow delegatecall
  */
 abstract contract ERC1967Upgrade is ERC1967Storage {

contracts/proxy/utils/UUPSUpgradeable.sol

@@ -10,6 +10,8 @@ import "../ERC1967/ERC1967Upgrade.sol";
  * continuation of the upgradability.
  *
  * The {_authorizeUpgrade} function MUST be overridden to include access restriction to the upgrade mechanism.
+ *
+ * _Available since v4.1._
  */
 abstract contract UUPSUpgradeable is ERC1967Upgrade {
     function upgradeTo(address newImplementation) external virtual {

contracts/token/ERC20/extensions/IERC20Metadata.sol

@@ -6,6 +6,8 @@ import "../IERC20.sol";
 
 /**
  * @dev Interface for the optional metadata functions from the ERC20 standard.
+ *
+ * _Available since v4.1._
  */
 interface IERC20Metadata is IERC20 {
     /**

contracts/token/ERC20/extensions/draft-ERC20FlashMint.sol

@@ -11,6 +11,8 @@ import "../ERC20.sol";
  *
  * Adds the {flashLoan} method, which provides flash loan support at the token
  * level. By default there is no fee, but this can be changed by overriding {flashFee}.
+ *
+ * _Available since v4.1._
  */
 abstract contract ERC20FlashMint is ERC20, IERC3156FlashLender {
     bytes32 constant private RETURN_VALUE = keccak256("ERC3156FlashBorrower.onFlashLoan");

contracts/token/ERC20/extensions/draft-ERC20Permit.sol

@@ -77,6 +77,8 @@ abstract contract ERC20Permit is ERC20, IERC20Permit, EIP712 {
 
     /**
      * @dev "Consume a nonce": return the current value and increment.
+     *
+     * _Available since v4.1._
      */
     function _useNonce(address owner) internal virtual returns (uint256 current) {
         Counters.Counter storage nonce = _nonces[owner];

contracts/utils/Multicall.sol

@@ -6,6 +6,8 @@ import "./Address.sol";
 
 /**
  * @dev Provides a function to batch together multiple calls in a single external call.
+ *
+ * _Available since v4.1._
  */
 abstract contract Multicall {
     /**

contracts/utils/StorageSlot.sol

@@ -26,7 +26,7 @@ pragma solidity ^0.8.0;
  * }
  * ```
  *
- * Available since v4.1.0 for `address`, `bool`, `bytes32`, and `uint256`.
+ * _Available since v4.1 for `address`, `bool`, `bytes32`, and `uint256`._
  */
 library StorageSlot {
     struct AddressSlot {

contracts/utils/cryptography/ECDSA.sol

@@ -31,7 +31,7 @@ library ECDSA {
 
         // Check the signature length
         // - case 65: r,s,v signature (standard)
-        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098)
+        // - case 64: r,vs signature (cf https://eips.ethereum.org/EIPS/eip-2098) _Available since v4.1._
         if (signature.length == 65) {
             // ecrecover takes the signature parameters, and the only way to get them
             // currently is to use assembly.

contracts/utils/cryptography/SignatureChecker.sol

@@ -13,6 +13,8 @@ import "../../interfaces/IERC1271.sol";
  *
  * Note: unlike ECDSA signatures, contract signature's are revocable, and the outcome of this function can thus change
  * through time. It could return true at block N and false at block N+1 (or the opposite).
+ *
+ * _Available since v4.1._
  */
 library SignatureChecker {
     function isValidSignatureNow(address signer, bytes32 hash, bytes memory signature) internal view returns (bool) {