docs: Update documentation for controller PR #1769 (#42)

Updates documentation to reflect changes made in:
    fix: switch precedence of cartridgeChains and provided chains

    Related controller PR: cartridge-gg/controller#1769

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

Author: 3 people

src/pages/controller/configuration.md

@@ -16,7 +16,7 @@ export type Chain = {
 
 export type ControllerOptions = {
     // Chain configuration
-    chains?: Chain[];  // Custom RPC endpoints for slot katana instances
+    chains?: Chain[];  // Custom RPC endpoints (takes precedence over default chains)
     defaultChainId?: string;  // Default chain to use (hex encoded). If using Starknet React, this gets overridden by the same param in StarknetConfig
 
     // Session options 
@@ -29,6 +29,30 @@ export type ControllerOptions = {
 };
 ```
 
+## Chain Configuration
+
+Controller provides default Cartridge RPC endpoints for Starknet mainnet and sepolia networks:
+- `https://api.cartridge.gg/x/starknet/mainnet`
+- `https://api.cartridge.gg/x/starknet/sepolia`
+
+When you provide custom chains via the `chains` option, they take precedence over the default Cartridge chains if they specify the same network. This allows you to:
+- Use custom RPC endpoints for mainnet or sepolia
+- Add support for additional networks (like Slot katana instances)
+- Override default chain configurations
+
+**Example:**
+```typescript
+const controller = new Controller({
+  chains: [
+    { rpcUrl: "https://api.cartridge.gg/x/my-game/sepolia" }, // Overrides default sepolia
+    { rpcUrl: "http://localhost:5050" }, // Adds local development chain
+  ],
+  chainId: constants.StarknetChainId.SN_SEPOLIA,
+});
+```
+
+## Configuration Categories
+
 The configuration options are organized into several categories:
 
 -   **Chain Options**: Core network configuration and chain settings