* fix: remove relURL from markdown render image hook
BREAKING CHANGE: As the relURL function in markdown render hooks
caused some unwanted side effects we had to remove it. Related to this
change the behavior for sites deployed to a subdirectory has changed as
well! Please check the [documentation](https://geekdocs.de/usage/getting-started/#sub-directories)
how to workaround subdirectory deployments.
* restructure color-schemes page to work as image bundle example
* fix wording
BREAKING CHANGE: The include shortcode will render files as Markdown
instead of HTML by default now. While the Markdown renderer should be
able to render HTML as well this might still work as before.
BREAKING CHANGE: The include shortcode option markdown was replaces by
a generic type option that could be used to specify special include
types.
