updated playlist import doc

[jamiul-islam]

• updated the Spotify import doc
• added walkthrough gif in public directory
• showed the gif in the markdown
• added a youtube walkthrough to the gif

video which I added: https://youtu.be/3Ncz-IJqmTA

[watsonbox]

Thanks a lot for the thought, though I don't feel this really adds much that isn't already fairly clear from the existing description.

I know I've mentioned "Excel", but I'm also not that keen to add links to examples on YouTube, especially when specific to Windows and Google Sheets.