fix: remove relURL from markdown render image hook (#93)

* 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

layouts/_default/_markup/render-image.html

@@ -1,2 +1,2 @@
-<img src="{{ .Destination | safeURL | relURL }}" alt="{{ .Text }}" {{ with .Title}} title="{{ . }}"{{ end }} />
+<img src="{{ .Destination | safeURL }}" alt="{{ .Text }}" {{ with .Title}} title="{{ . }}"{{ end }} />
 {{- /* Drop trailing newlines */ -}}