Enable @mention notation for personas

When entering descriptions of various parts of the data model, it would be useful to be able to cite or otherwise mention personas.  This could take the form of @ notation, or similar, which would provide a quick search capability. 

This would make writing simple use cases very easy.

One spin-off benefit of this, is that you could then go to the persona page and take a look at that persona's "@mentions", almost as if they were a real user, and this would give a really good impression of that persona's "life" within the product.