chore(public): Update Premit2 SDK Readme with links and examples

sdks/permit2-sdk/README.md

@@ -1,4 +1,89 @@
-# permit2-sdk
+# Permit2 SDK
+
+The Permit2 SDK provides utilities for interacting with the Permit2 contract, enabling efficient token approvals and transfers.
+
+## Learn More
+- [Introducing Permit2 and Universal Router](https://blog.uniswap.org/permit2-and-universal-router)
+- [How to Integrate with Permit2](https://blog.uniswap.org/permit2-integration-guide)
+- [Permit2 Documentation](https://docs.uniswap.org/contracts/permit2/overview)
+
+## Installation
+
+```bash
+npm install @uniswap/permit2-sdk
+```
+
+## Quick Start
+
+Here are basic examples of how to use the Permit2 SDK to generate a signature for a PermitSingle using Ethers v5:
+
+### Frontend (Browser) Example
+
+```typescript
+import { ethers } from 'ethers'
+import { AllowanceProvider, AllowanceTransfer, PERMIT2_ADDRESS, PermitSingle, MaxAllowanceTransferAmount } from '@uniswap/permit2-sdk'
+
+async function frontendExample() {
+  // Setup (using Ethers v5)
+  const provider = new ethers.providers.Web3Provider(window.ethereum)
+  const signer = provider.getSigner()
+  const chainId = await provider.getNetwork().then(network => network.chainId)
+
+  // Get the next valid nonce
+  const allowanceProvider = new AllowanceProvider(provider, PERMIT2_ADDRESS)
+
+  const tokenAddress = '0x...'; // Replace with actual token address
+  const ownerAddress = await signer.getAddress(); // Retrieve the owner's address
+  const spenderAddress = '0x...'; // Replace with actual spender address
+
+  // Call getAllowanceData to get the allowance data
+  const allowanceData = await allowanceProvider.getAllowanceData(tokenAddress, ownerAddress, spenderAddress);
+  const { nonce, amount, expiration } = allowanceData;
+
+  // NOTE: If the allowance is enough and the expiration is still valid, you can skip the permit
+
+  // Construct the PermitSingle object
+  const permitSingle: PermitSingle = {
+    details: {
+      token: tokenAddress,
+      amount: MaxAllowanceTransferAmount,
+      expiration: Math.floor((Date.now() + 30 * 24 * 60 * 60 * 1000) / 1000), // 30 days
+      nonce,
+    },
+    spender: spenderAddress,
+    sigDeadline: Math.floor((Date.now() + 30 * 60 * 1000) / 1000), // 30 minutes
+  }
+
+  // Get the permit data
+  const { domain, types, values } = AllowanceTransfer.getPermitData(permitSingle, PERMIT2_ADDRESS, chainId)
+
+  // Sign the permit
+  const signature = await signer._signTypedData(domain, types, values)
+
+  // Now you can use `permitSingle` and `signature` in your contract calls
+}
+```
+
+### Backend (Node.js) Example
+
+```typescript
+async function backendExample() {
+  // Setup (using Ethers v5)
+  const provider = new ethers.providers.JsonRpcProvider('YOUR_RPC_URL')
+  const privateKey = 'YOUR_PRIVATE_KEY'
+  const signer = new ethers.Wallet(privateKey, provider)
+
+  // same as Frontend Example...
+}
+```
+
+Note: These examples use Ethers v5. If you're using a different version, you may need to adjust the code accordingly.
+
+## Key Concepts
+
+- **PermitSingle**: Represents a single token approval.
+- **AllowanceProvider**: Helps retrieve current allowance data.
+- **AllowanceTransfer**: Provides methods to generate permit data for signing.
 
 ## Local Development