Add iron vault to users

Author: zkat

src/index.md

@@ -108,6 +108,7 @@ of some examples of KDL in the wild (either v1, v2, or both):
 * [fmod-rs](https://github.com/CAD97/fmod-rs) - Rust bindings to FMOD Core and FMOD Studio
 * [mise](https://mise.jdx.dev/) - dev tools, env vars, task runner
 * [Camping](https://github.com/camping/camping) - Ruby web microframework
+* [Iron Vault](https://ironvault.quest) - VTT (Virtual Tabletop) plugin for Obsidian for the Ironsworn family of games
 * You?
 
 </section>