[Portal] Update docs for useActiveWallet (#4352)

## Problem solved

Short description of the bug fixed or feature added

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## PR-Codex overview
The focus of this PR is to enhance the `useActiveWallet` hook by adding examples demonstrating its usage for account and network change events.

### Detailed summary
- Added examples for basic usage, account change event, multiple accounts changed event, and network change event in the `useActiveWallet` hook.

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Author: kien-ngo

packages/thirdweb/src/react/core/hooks/wallets/useActiveWallet.ts

@@ -5,11 +5,40 @@ import { useConnectionManagerCtx } from "../../providers/connection-manager.js";
  * A hook that returns the active wallet
  * @returns The active `Wallet` or `undefined` if no active wallet is set.
  * @example
+ *
+ * ### Basic usage
  * ```jsx
  * import { useActiveWallet } from "thirdweb/react";
  *
  * const wallet = useActiveWallet();
  * ```
+ *
+ * ### Listen to account change event
+ * ```jsx
+ * const wallet = useActiveWallet();
+ *
+ * wallet?.subscribe("accountChanged", (account) => {
+ *   console.log(account);
+ * });
+ * ```
+ *
+ * ### Listen to multiple accounts changed event
+ * ```jsx
+ * const wallet = useActiveWallet();
+ *
+ * wallet?.subscribe("accountsChanged", (addresses) => {
+ *   console.log(addresses);
+ * });
+ * ```
+ *
+ * ### Listen to network change event
+ * ```jsx
+ * const wallet = useActiveWallet();
+ *
+ * wallet?.subscribe("chainChanged", (chain) => {
+ *   console.log(chain);
+ * });
+ * ```
  * @walletConnection
  */
 export function useActiveWallet() {