Adds promo for My Vinyls

[mcomisso]

Checklist

• [x] The link is freely available for everyone to read.
• [x] The link hasn't already been submitted.
• [x] I placed the link at the bottom of its category.
• x ] The link is in the correct format: [Post name](link to post) from [Author name](optional author link). For example, [My WWDC 2020 Wishlist](https://beckyhansmeyer.com/2020/05/13/my-wwdc-2020-wishlist/) from Becky Hansmeyer.
• [x] The link isn't about rumors.
• [x] The linked material is suitable for a general audience.

Optional for links to paid products

• [x] The link regards a discounted paid product. I put it in the Offers category.
• [x] This is the only Offers link I have submitted or updated. (Send just one link for multiple offers to avoid overwhelming the list.)