Improve the appearance of social media link previews

[alilleybrinker]

When sharing links on social media, most platforms use a well-defined set of meta tags on a page to produce helpful informational "preview" blocks, that generally include a title, description, and possibly an image for the link.

Currently, sharing links to CVE records produces a preview that only shows the URL, which itself only includes the CVE ID, and so the preview says nothing about the content of the CVE record.

It would be good to amend the meta tags generated at least on CVE record pages to start, so they include the title and description of the CVE record.

Here's an example, from this post: https://bsky.app/profile/alilleybrinker.com/post/3lo4uivra6k22