At the moment, it doesn't look like Flarum (the forum software I'm using) supports adding dynamic tags on a post, I have to define them before hand. Which also makes the current list of tags an experiment, I'll add/remove them as content starts to take shape.
For now, if there isn't a proper tag, I'd suggest posting in the general section. If enough users start posting about Vagrant, I'll make a tag. :-)