Please specify the license in this repository and in the submodules

[mersinvald]

If the license is left unspecified, the default is "all rights reserved", which restricts copying and modification of the source code in this repository and in your QMK modules.

I am not sure if the GPL forces any obligations in this case, and if it considers this work derivative to qmk_firmware, but to be on the safe side I'd recommend using GNU GPLv2 as well.

[mersinvald]

Keep in mind that LICENSE file would cover the whole repo, so you might want to explicitly state that the article is published under a different license, if you chose to go with the GPL for the code.

[optozorax]

Ok, I will move out the article, and change the license of this repo and of the submodules to GNU GPLv2 like in the QMK. But this must take some time...