Adds og:image:width and og:image:height to the global head so LinkedIn
(and friends) reliably render the large preview card instead of a tiny
thumbnail. The image and the rest of the Open Graph tags were already in
good shape, so this is the missing piece. Also adds a website README
documenting how the cards work and the gotchas.
Co-authored-by: GeekTrainer <GeekTrainer@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Christopher Harrison