build-commit-from: Document missing options
build-commit-from: Document missing options

Document --end-of-life, --timestamp and --disable-fsync.

Closes: #2498
Approved by: matthiasclasen

flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak