* change "pmbootstrap kconfig_check" to "pmbootstrap kconfig check"
* change "pmbootstrap menuconfig" to "pmbootstrap kconfig edit [-x|-g]"
(with legacy alias, because the first syntax was referenced to a lot)
* enable X11 interfaces: -x: xconfig, -g: gconfig
* new function to copy the xauthority file:
pmb.chroot.other.copy_xauthority()
* remove menufconfig() function from the kernel template and all kernel
aports ([skip ci] because it would rebuild all kernels and run out of
time). Alpine has dropped this as well, and it wouldn't work with the
new code anyway.
* Change `pmbootstrap flasher flash_system` command to
`pmbootstrap flasher flash_rootfs`
* The old command still works, but all references have been changed to
the new command
* Remove obsolete `pmbootstrap flasher export` (that was changed to
`pmbootstrap export` a few months ago)
* Update `README.md` and ZSH auto completion
* Change the description of the generated rootfs image (not talking
about a system image anymore, mention that it has subpartitions)
* Better description of `pmbootstrap flasher flash_rootfs --partition`