Editora 0.10.0. Archived, so links from that release keep working. Read the 0.18.3 page →
Diagram: Set PlantUML Command…
diagram.setPlantumlCommand Set the path or command used to run the PlantUML executable.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Diagram: Set PlantUML Command…, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.