Use github style warning in readme

README.md

@@ -53,7 +53,8 @@ Transparent proxies have an _admin_ address which has the rights to upgrade them
 
 The proxy admin contract also defines an _owner_ address which has the rights to operate it. By default, this address is the `initialOwner` address used during deployment of the transparent proxy if provided, otherwise it is the externally owned account used during deployment. You can change the proxy admin owner by calling the `admin.transferProxyAdminOwnership` function in the Hardhat plugin, or the `transferOwnership` function of the proxy admin contract if using Foundry.
 
-WARNING: Do not reuse an already deployed `ProxyAdmin`. Before `@openzeppelin/contracts` version 5.x, the address provided to transparent proxies was an `initialAdmin` as opposed to an `initialOwner` of a newly deployed `ProxyAdmin`. Reusing a `ProxyAdmin` will disable upgradeability in your contract.
+> [!WARNING]
+> Do not reuse an already deployed `ProxyAdmin`. Before `@openzeppelin/contracts` version 5.x, the address provided to transparent proxies was an `initialAdmin` as opposed to an `initialOwner` of a newly deployed `ProxyAdmin`. Reusing a `ProxyAdmin` will disable upgradeability in your contract.
 
 UUPS and beacon proxies do not use admin addresses. UUPS proxies rely on an [`_authorizeUpgrade`](https://docs.openzeppelin.com/contracts/api/proxy#UUPSUpgradeable-_authorizeUpgrade-address-) function to be overridden to include access restriction to the upgrade mechanism, whereas beacon proxies are upgradable only by the owner of their corresponding beacon.