Remove document.RenderMarkdown function
Remove document.RenderMarkdown function

The function has been deprecated since some releases and we now remove
it finally because it is not used any more in the library.

Signed-off-by: Sascha Grunert <70ab469ddb2ac3e35f32ed7c2fd1cca514b2e879@suse.com>

kubernetes/release,kubernetes/release