Page Published Incorrectly to RSS

This morning (May 23) my RSS feed somehow connected to a Google doc on my website and, via Mailchimp, sent the page out to my followers. I was wondering if anyone can spot how this happened and how to avoid this error in the future.

Here’s my RSS feed: https://macflynn.com/feed/

Here’s the Google doc page: https://macflynn.com/printable-book-list/

Thanks for any help!