add dummy default.nix

fix nix-env evaluation

nix-env picked up `default.nix`, which contained our hardware profiles.
This is not only cpu-intensive to evaluate but also fails because
it does some import-from-derivation.
By moving default.nix to release.nix it should be no longer loaded

lenovo x1 carbon gen6: update S3 suspend

With UEFI >= 1.30, there's an explicit option to enable S3 power management.
Once this is selected, S3 is enabled and "deep" is selected as the default
/sys/power/mem_sleep value without requiring any kernel boot parameters.

This adds basic support for the Thinkpad T440s, based on the work done for the T440p. The expression enables:

- microcode updates
- trackpoint support
- kernel module for battery level management

common/cpu: default microcode updates to enableRedistributableFirmware

copy of #81

lenovo/thinkpad/t450s: init

- BeagleBoard PocketBeagle
- PC Engines APU
- Purism Librem 13v3

thinkpad: introduce t430

Copied everything from t440p, added a fix for the brightness keys

lenovo/thinkpad/x260: Init

Fix unusable Lenovo Thinkpad X1 profile

As proposed by @garbas in #60

[rebased from #67] Suggestions for CONTRIBUTING

cpu/intel: early KMS

Add Toshiba Chromebook 2 (swanky), Org -> Markdown