Introduce tag aliases

[corvus-ch]

Given a have a tag named "HyperText Markup Language"
When I mention "HTML" in a fragment
Then it should be linked to the tag named "HyperText Markup Language"

I have quite some cases where I have tags that are often referred to by abbreviations but sometimes also by its no abbreviated form.

My current solution is to create the abbreviated form as child of the non abbreviated but I would prefer if I just could add the abbreviation as an alias.