Editora 0.11.0. Archived, so links from that release keep working. Read the 0.16.0 page →
Edit: Toggle Completion Documentation
edit.completionDoc Show or hide the documentation popup beside the completion list.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Edit: Toggle Completion Documentation, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.