Docs remove legacy enc key arg (#6220)

Closes TOOL-3348

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## PR-Codex overview
This PR focuses on simplifying the instantiation of the `InAppWalletOptions` by removing the `encryptionKey` parameter from its constructor calls.

### Detailed summary
- Removed `encryptionKey: "myencryptionkey"` from the first instance of `InAppWalletOptions`.
- Removed `-encryptionKey: "myencryptionkey"` from the second instance of `InAppWalletOptions`.

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Author: 0xFirekeeper

apps/portal/src/app/unity/v5/wallets/in-app-wallet/page.mdx

@@ -107,7 +107,7 @@ var inAppWalletOptions = new InAppWalletOptions(
 ### Login with Custom Auth - OIDC Compatible
 
 ```csharp
-var inAppWalletOptions = new InAppWalletOptions(authprovider: AuthProvider.JWT, jwtOrPayload: "myjwt", encryptionKey: "myencryptionkey");
+var inAppWalletOptions = new InAppWalletOptions(authprovider: AuthProvider.JWT, jwtOrPayload: "myjwt");
 var options = new WalletOptions(
     provider: WalletProvider.InAppWallet, 
     chainId: 1, 
@@ -121,8 +121,7 @@ var wallet = await ThirdwebManager.Instance.ConnectWallet(options);
 ```csharp
 var inAppWalletOptions = new InAppWalletOptions(
     authprovider: AuthProvider.AuthEndpoint, 
-    jwtOrPayload: "mypayload", 
-    encryptionKey: "myencryptionkey"
+    jwtOrPayload: "mypayload"
 );
 var options = new WalletOptions(
     provider: WalletProvider.InAppWallet,