The .gitignore file was modified to remove the zmk-config directory from the ignored list. This change lets us monitor the directory's modifications, enhancing the management of
VS Code can't share two folders with a Docker container at the same time, so
to build with -DZMK_CONFIG the zmk-config repo needs to be a subfolder of the
zmk repo. Added zmk-config to .gitignore to allow this.
