Add a kernel version in dracut command-line options.

This script allows to by-pass shacache/shadir: execute ```40upload-image.sh```
instead of ```35install-image-directly.sh```.

- Do not enable EFI STUB mode when compiling the kernel. dracut already
  takes care of embedding an efi stub in the efi application image. See
dracut options "uefi" and "uefi_stub".
- Add examples of .config tampering (but comment them all for now).

For an explanation of the problem those keys was working around and a
resolution thereof, see
https://www.erp5.com/group_section/forum/Need-help-to-fix-shacache-upload-SEiYkNyXWq/view?list_start=8&reset=1#2061505002