livepatch: Add some basic LivePatch documentation

[Jessica Yu]

+++ Petr Mladek [25/04/16 17:14 +0200]:
>LivePatch framework deserves some documentation, definitely.
>This is an attempt to provide some basic info. I hope that
>it will be useful for both LivePatch producers and also
>potential developers of the framework itself.
>
>Signed-off-by: Petr Mladek <pmladek at suse.com>

Nice work Petr. I read through it and didn't notice any other
additional issues. With Chris', Balbir's and Josh's comments taken
into account:

Acked-by: Jessica Yu <jeyu at redhat.com>