Replaced `<zephyr/zephyr.h>` with `<zephyr/kernel.h>` based on the following compilation warning raised:

	#warning "<zephyr/zephyr.h> is deprecated, include <zephyr/kernel.h> instead" [-Wcpp]

Note: This change has been applied to the basic-sample only. Most likely other samples in the project might require the same update.

…sic-sample in macOS setup guide

Convenient for when already having Git cloned everything some other moment, and you just want to build and flash the basic sample from the correct directory.

…tructure.md

To ensure the image displays correctly in the web version of the tutorial, I added two parent directory references to the path '/images/2-introduction/sample-folder.png'.

…structure.md

To ensure all images on the zephyr-structure.md display correct in the web version of the tutorial, I added two parent directory references to the following paths as well:

![k-config](../../images/2-introduction/k-config.png)
![guiconfig](../../images/2-introduction/guiconfig.png)
![basic-sample](../../images/2-introduction/basic-sample.png)

All image paths that include `images/` and `svg-images/` should now be referenced correctly. These path edits are based on testing them within my webbrowser, but couldn't test on my own fork directly (still need to figure out how to make GitHub Pages work myself).

…orial

…tibility

This commit attempts all images being properly displayed when accessed in both the GitHub web interface, as in GitHub Pages (Jekyll). So far images were only linked successfully when accessed via the GitHub web interface, but not in GitHub Pages. Important to mention thought: this change is a preliminary first test.

- Added `baseurl: "/zephyr-rtos-tutorial"` to `_config.yml` to set a base path configuration for Jekyll.
- Updated all image paths in the documentation to use `{{ site.baseurl }}` instead of `../../` parent references.

…guration

- Restored image paths in documentation back to original links (`/images`), reversing the application of `{{ site.baseurl }}`. Although Jekyll should be able to process `{{ site.baseurl }}` into working images in GitHub Pages, the GitHub web interface apparently is not able to handle this.
- Path evolution for clarity:
  - Original:    /images
  - Attempt 1:   /../../images
  - Attempt 2:   {{ site.baseurl }}/images
  - This commit: /images
- Purposefully kept `baseurl: "/zephyr-rtos-tutorial"` unchanged in `_config.yml`. Maybe having this line in the configuration file will already be able to solve the incorrect image paths in Jekyll. Fingers crossed...

…uration

- Restored image paths in documentation back to original links (`/images`), reversing the application of `{{ site.baseurl }}`. Although Jekyll should be able to process `{{ site.baseurl }}` into working images in GitHub Pages, the GitHub web interface apparently is not able to handle this.
- Path evolution for clarity:
  - Original:    /images
  - Attempt 1:   /../../images
  - Attempt 2:   {{ site.baseurl }}/images
  - This commit: /images
- Purposefully kept `baseurl: "/zephyr-rtos-tutorial"` unchanged in `_config.yml`. Maybe having this line in the configuration file will already be able to solve the incorrect image paths in Jekyll. Fingers crossed...

…orial

…solution to solve Jekyll error

Because of the following error raised: "/usr/local/bundle/gems/jekyll-3.9.5/lib/jekyll/tags/include.rb:121:in `locate_include_file': Could not locate the included file 'incomplete.md' in any of ["/github/workspace/docs/_includes", "/usr/local/bundle/gems/jekyll-theme-primer-0.6.0/_includes"]. Ensure it exists in one of those directories and is not a symlink as those are not allowed in safe mode. (IOError)"

…g file