[Merge] ~xnox/grub:initrdless-docs into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu

[Dimitri John Ledkov]

The general concept is to show something:

1) upon update-grub
2) before initrdless boot is attempted (grub output might not be visible)
3) before initrdfull fallback is attempted (grub output might not be visible)
4) log kmsg/journal from running system when fallback got triggered (should be visible)
-- 
https://code.launchpad.net/~xnox/grub/+git/grub/+merge/392866
Your team Ubuntu Core Development Team is requested to review the proposed merge of ~xnox/grub:initrdless-docs into ~ubuntu-core-dev/grub/+git/ubuntu:ubuntu.