Closes #133

thanks for the link in #103

put some emphasis on choosing an image and support flashing any 4M image
externally.

All we do is the bios vendor/version check. We can do that in any case.
Requirements don't change.

thanks @alex-kazda

Fixes #85

this actually got lost during updates for the release.

For creating USB bios images from Lenovo's BIOS, we shouldn't duplicate
instructions. Things might change and break for users that way.

see #77

We recently added that the whole 8M chip flashing is optional, which is
important indeed. In brough some more stuff in which may be confusion.

We don't want to mention one specific OS because we're really generic
people should try to install whatever they want.

Also, "the command defaults to..." is misleading, as there are commandline
options applied in our example. Remove that.

And lastly, as long as users make the backups we always suggest in the
examples, they can change things at any time.

Despite I've never had any problems, applying external voltage to the
flash is considered dangerous, see #49 and #68. So change our documentation to
suggest not to do this often. Also, remove the note about "WoL power"
not being necessary. We don't document that (yet) anyways.

Fixes #68

see #65

Fixes #56
Closes #58

This simplifies setup by remove the unneeded RAM voltage checking.

According to the spec, DDR3L RAM has to work using 1.5V, see
https://en.wikipedia.org/wiki/DDR3_SDRAM#DDR3L_and_DDR3U_extensions.
Coreboot simply doesn't always implement changing voltage, which
can never prevent RAM from working though.

Closes #50
Fixes #38

First-time installation link was missing a dash

Closes #47

We already have a config for a more free version using SeaVGABIOS. From now
on we build, test and release that too. The image filename should just
contail _free_ which is probably enough.

Closes #32

We have to do this for the release, see #34