Update README.md with STETH instructions

README.md

@@ -92,7 +92,50 @@ const unwrapWETH = new UnwrapWETH(amountWETH, chainId, optionalPermit2Params)
 const { calldata, value } = SwapRouter.swapCallParameters([unwrapWETH, seaportTrades, looksRareTrades])
 ```
 
-### Trading stETH by automatically wrapping to wstETH
+### Trading stETH
+To trade stETH as an input token, you can make sure the router automatically wraps stETH to wstETH before trading across a wstETH route.
+```typescript
+import { TradeType } from '@uniswap/sdk-core'
+import { Trade as V2TradeSDK } from '@uniswap/v2-sdk'
+import { Trade as V3TradeSDK } from '@uniswap/v3-sdk'
+import { MixedRouteTrade, MixedRouteSDK, Trade as RouterTrade } from '@uniswap/router-sdk'
+import {
+  UniswapTrade,
+  WrapSTETH
+} from "@uniswap/universal-router-sdk";
+
+// including optional permit2 parameter will transfer STETH amount using permit2 
+const wrapSTETH = new WrapSTETH(inputSTETH, 1, WrapSTETHPermitData?, wrapAmountOtherThanContractBalance?)
+const uniswapWstethTrade = new UniswapTrade(
+  new RouterTrade({ v2Routes, v3Routes, mixedRoutes, tradeType: TradeType.EXACT_INPUT }),
+  { slippageTolerance}
+)
+
+const { calldata, value } = SwapRouter.swapCallParameters([wrapSTETH, uniswapWstethTrade])
+```
+
+To recieve stETH as an output token, you can make sure the router automatically unwraps wstETH to stETH before returning to the swapper
+```typescript
+import { TradeType } from '@uniswap/sdk-core'
+import { Trade as V2TradeSDK } from '@uniswap/v2-sdk'
+import { Trade as V3TradeSDK } from '@uniswap/v3-sdk'
+import { MixedRouteTrade, MixedRouteSDK, Trade as RouterTrade } from '@uniswap/router-sdk'
+import {
+  ROUTER_AS_RECIPIENT,
+  UniswapTrade,
+  UnwrapSTETH
+} from "@uniswap/universal-router-sdk";
+
+// return trade to the router instead of the recipient using the ROUTER_AS_RECIPIENT constant so that the router may custody tokens to unwrap
+const uniswapWstethTrade = new UniswapTrade(
+  new RouterTrade({ v2Routes, v3Routes, mixedRoutes, tradeType: TradeType.EXACT_INPUT }),
+  { slippageTolerance, ROUTER_AS_RECIPIENT}
+)
+const unwrapSTETH = new UnwrapSTETH(recipient, aountMinimum, chainId)
+
+const { calldata, value } = SwapRouter.swapCallParameters([uniswapWstethTrade, unwrapSTETH])
+```
+
 
 ## Running this package
 Make sure you are running `node v16`