Fix list formatting in kubeadm setup tutorial

There is an issue with ordered lists in the Creating HA clusters with
kubeadm setup tutorial. All list items are labeled 1. This is because
the underlying markdown processor for Hugo, blackfriday, requires
list items with multiple paragraphs to have four space indentation.
See (russross/blackfriday#244)

This commit adds an extra space before paragraphs in lists so they are
correctly interpreted as multi-paragraph lists.

However, this exposes a bug in blackfriday where lines beginning with
`-` in codefenced code blocks inside lists are parsed as sub-lists.
This means code fenced code blocks inside lists that contain yaml are
malformed. (See russross/blackfriday#239)

So this commit mitigates this bug in two situations. It uses a 4-space
indented code block in one situation. In another situation where a list
only contained one element, it is no longer a list.