Add code formatter for Markdown

[MoritzWeber0]

So far, prettier formats our HTML and SCSS files. It doesn't change the Markdown files. The main benefit of auto-formatting Markdown files is the automatic wrapping of lines, making it easier to read.

I tried:

• prettier without additional plugins and proseWrap: always ➡️ Breaks shortcodes
• prettier-plugin-hugo-post with proseWrap: always ➡️ Works better, but breaks self-closing shortcodes and sometimes moves shortcode sections in one line.

Requirements:

• Auto-wrap lines after 80 characters (to be able to view the content on smaller displays)

• Place each shortcode opening or closing tag in a new line:

  {{% highlight important %}}
  Example
  {{% /highlight %}}

  instead of

  {{% highlight important %}} Example {{% /highlight %}}

We might need to write our own formatter to achieve the goals.