Found the bug!
Issues are 1) there is a hashtag symbol where there should be a forward slash, 2) front matter slug has been changed, but mainly 3) the url is pointing to the old relative url slug that is shipped with the docusaurus default dev environment.
Bug is not fixed by pointing to resolved
Here's how the bug was fixed. The link was changed to point to info about Front Matter within the docusaurus developer reference documentation.
Gitub Deployment Status
Vercel Production Build Status (Ready = SUCCESS)