I just encountered confused user that used opkg instead of opkg-cl and
migration scripts broke his system. The same thing can happen if someone
tries to perform this on Turris OS 4.0+.

I found out why lcoalrepo fails. It was because move failed because of
non-existent target directory. Removing it is temporally fix and once we
push final fix to HBS we can drop this removal line from documentation.

Just to make it clear that migration is performed to Turris OS 5.0 and
not to 4.0.

The plan is to release Turris OS 5.1 releases so this prepares it for
that. It limits listed changelogs for Turris OS 5.0.x only.

To simplify understanding HBS can be mapped also to Stable and HBT to
Testing. This can ease some confusion among users.

Document serial boot procedure on Turris MOX

See merge request !99

- The current version of Turris OS is included in module 'installed'. If we want to
know the image in the factory, there is module 'os_release'.

- Usually, dmesg and messages contain same stuff. Replace dmesg by
disk_full

the medkit hash is calculated based on sha256 and not on sha512

Perhaps it's weird to mention future in "history", but why not?