Add a step specifying how to use Dump Mii NAND

[JamesBarwell]

This is the first time in the process that an app is launched. Having clicked on the app name, I assumed that the app was already running, so was confused to see buttons "Delete" and "Load". The first time round it's not obvious that this is just the launcher's menu, so it wasn't obvious what these buttons do! Would be good to make this step explicit. Thanks.