Editora 0.10.0. Archived, so links from that release keep working. Read the 0.18.5 page →
GitHub: Open File on GitHub
github.openOnGitHub Open the active file at the caret line on GitHub in your browser.
How to run it
Open the command palette (M-x in the Emacs keymap) and search for GitHub: Open File on GitHub, then press Enter. It has no default keybinding, but you can bind one in Settings → Keymaps.