
This screen shot description corresponds to installation step 3, which instructs: Enable Markdown for posts & pages, by manually checking the checkbox at: <strong>Settings > Writing > 'Use Markdown for posts and pages'</strong>
This is a simple plugin to help you write posts or pages in plain-text Markdown syntax. And even allowing plaint-text Markdown for comments as well. It will also switch-off the Visual Editor, as you don’t need distractions. This plugin sits on top of a giant’s shoulder, namely Jetpack.
This plugin is also installable via composer, see: https://github.com/7php/MarkItDownWordpress