updated description of using session keys with Engine (#6474)

Signed-off-by: Eiman <eabdelmoneim@gmail.com>
Signed-off-by: Joaquim Verges <joaquim.verges@gmail.com>
Co-authored-by: Joaquim Verges <joaquim.verges@gmail.com>
Co-authored-by: Jonas Daniels <jonas.daniels@outlook.com>
Co-authored-by: graphite-app[bot] <96075541+graphite-app[bot]@users.noreply.github.com>

Author: 4 people

apps/portal/src/app/engine/features/account-abstraction/page.mdx

@@ -64,12 +64,12 @@ Grant & revoke admins on an account with the `/contract/<chain>/<account_address
 
 Grant & revoke sessions on an account which allow specific wallets to interact with specified contracts for a given period of time with the `/contract/<chain>/<account_address>/account/sessions` endpoints.
 
-## Transact with an account
+## Transact with an account using session keys
 
 Make write calls with a smart account by calling a write endpoint and specify the `x-backend-wallet-address` and `x-account-address` headers.
 
-The `x-backend-wallet-address` should be set to the engine backend wallet that is an admin over the account.
+The `x-backend-wallet-address` should be set to the Engine backend wallet that has been granted signing permission by the smart account's admin through a [session key](https://portal.thirdweb.com/references/typescript/v5/erc4337/addSessionKey).
 
-The `x-account-address` should be set to the deployed account address itself.
+The `x-account-address` should be set to the deployed smart account address itself.
 
 Write calls made using these headers will initiate a `UserOperation` sent from the specified account.