Reading Mansoor Barri (4 Essential Markdown Tools) post on his Hugo website I want to highlight to everybody one tool that may be very usefull.
The tool is used to copy to clipboard any part of the website (overall a text) and pasting it to get equivalent in Markdown.
https://euangoddard.github.io/clipboard2markdown/
Its very nice way to migrate, page by page, from HTML to Markdown.
Have a look also on previously mentioned MarkdownDown