* 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
