Is there a way to add or edit the modules which show in multisite stores dashboard?

In multisite, Is there a way at all to add a custom module with instructions for each new user when setting up their store? (this can be in place of the welcome module seen here or perhaps I can actually modify this one?)

I need to be able to give new site owners some guidance and I need to use the available space in the centre of the dashboard to do so. Can anyone help please?