docs: Update documentation for controller PR #1899 (#63)

Updates documentation to reflect changes made in:
    feat: enable switch chain for external wallets

    Related controller PR: cartridge-gg/controller#1899

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

Author: tarrencev

src/pages/controller/configuration.md

@@ -39,6 +39,11 @@ When you provide custom chains via the `chains` option, they take precedence ove
 - Use custom RPC endpoints for mainnet or sepolia
 - Add support for additional networks (like Slot katana instances)
 - Override default chain configurations
+- Programmatically switch chains for connected external wallets (MetaMask, Rabby, WalletConnect)
+
+### External Wallet Chain Switching
+
+Controller supports programmatic chain switching for external wallets through the `externalSwitchChain` method. This allows applications to request connected external wallets to switch to different blockchain networks seamlessly.
 
 **Example:**
 ```typescript

src/pages/controller/signer-management.md

@@ -127,6 +127,38 @@ When connecting to your Controller:
 - Select any of your registered signers to authenticate
 - Your account and assets remain the same regardless of which signer you use
 
+### Chain Switching for External Wallets
+
+External wallets (MetaMask, Rabby, WalletConnect) support programmatic chain switching through the Controller interface. This allows applications to request that connected external wallets switch to a specific blockchain network.
+
+**Supported Functionality:**
+- **Automatic Chain Switching**: Applications can programmatically request external wallets to switch chains
+- **Cross-Chain Compatibility**: Works with Ethereum, Starknet, and other supported networks
+- **Seamless Integration**: No additional user interaction required beyond the wallet's own confirmation
+
+**How It Works:**
+1. Your application calls the chain switch method through the Controller
+2. The request is forwarded to the connected external wallet
+3. The wallet handles the chain switching process (may show user confirmation)
+4. The application receives confirmation of the successful chain switch
+
+**Example Usage:**
+```typescript
+// Switch connected external wallet to a different chain
+const success = await controller.externalSwitchChain(
+  walletType, // e.g., "metamask", "rabby"
+  chainId     // Target chain identifier
+);
+
+if (success) {
+  console.log("Chain switched successfully");
+} else {
+  console.log("Chain switch failed or was cancelled");
+}
+```
+
+**Note:** Chain switching availability depends on the specific external wallet's capabilities and the target chain support.
+
 ## Security Considerations
 
 ### Best Practices