Just a few notes:
This software is powered by Node.js and built on Redis database. When installed, NodeBB will have two default themes, Bootstrap and Lavender.
It also supports MongoDB and LevelDB out of the box.
The theme is called "Vanilla", it bases on Bootstrap (as does Lavender) and is skinable (e.g. with Bootswatch skins).
Add contents to Sidebar
I'd mention sth. like "widget system" since whether it's a sidebar or whatever depends on the theme but ok.
You could add the fact that NodeBB uses Markdown as preferred post-syntax, I don't know about the syntax-usage of the others but it may be worth researching