This is an example code using another nav-item to show the title "Site Administration".

I personally think this should be an <h1> but when I tried that it looked visually wrong and I preferred to not start changing a lot of CSS, but it would be nice if you could give it a try. I would also suggest changing the arrow to a Chevron arron and maybe using liferay-ui:icon instead of nav-item for it.

Also, after making these changes and liking them I wonder if we should also show the title "Control Panel" when we are there. Thoughts?