This is just what it says on the tin: the electron.d.ts from Electron's main distribution, minus the postinstall scripts.

(Why? Because if you want to use Electron APIs when writing plugins for apps like Obsidian, you don't need the Electron binaries, just the API definitions.)

Currently, the Electron version provided is 24.3.1, corresponding to the version used by the Obsidian 1.3.5 runtime, the previous major release of Obsidian.