Editora 0.10.0. Archived, so links from that release keep working. Read the 0.18.5 page →
View: Toggle Line Numbers
view.toggleLineNumbers Show or hide line numbers.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for View: Toggle Line Numbers, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.