Editora 0.10.0. Archived, so links from that release keep working. Read the 0.17.0 page →
Plugins: Set Registry URL…
plugins.setRegistryUrl Set the plugin registry index URL.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for Plugins: Set Registry URL…, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.