Does this create a bridge to DSTAR?
No. This document is to connect an XLX module to a Brandmeister Talkgroup. Brandmeister is a DMR network.
Should I build another Allstar node to add this to or could I do this on my current DMR bridge?
I don't know how your current bridge is configured. You're also discussing two different modes. D-Star and DMR are dissimilar modes, where D-Star is IMBE and DMR is AMBE. If the intention is to bridge a DMR network to D-Star, you will need to do some transcoding, which is out of scope for this document.
That being said, no you don't necessarily have to build another ASL node. You can run a second bridge for D-Star from the ASL node you currently have. A basic overview would be this:
D-Star <-> ASL <-> DMR
That setup will give you the following: