Update README repo latest blog posts when this repo has a push to main

[deeheber]

My README repo has a GH action workflow that needs to be manually run every time there's a new blog post published (I originally had it to run as a cron, but found the cron often didn't have much to update).

Update this repo to send a repository_dispatch event on merges to main to the README repo and on the README repo to trigger the Build README workflow when receiving this dispatch.

Possible solution