Fixed username links in the performance guide
These would end up being rendered as:
<a href="...">@yorickpeterse</a>
<a href="...">@yorickpeterse</a>[ci skip]
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
These would end up being rendered as:
<a href="...">@yorickpeterse</a>
<a href="...">@yorickpeterse</a>[ci skip]