So what makes a site compatible with onebox? I googled onebox and got to this github page: GitHub - discourse/onebox: A gem for turning URLs into website previews but for the framework I mentioned, they use Sphinx to auto-generate some of the pages so is there some settings the developpers can set with Sphinx to make their page compatible with onebox?
If you try to link https://docs.sunpy.org/en/v3.0.0/whatsnew/3.0.html in a line by itself you will see this message:
Sorry, we were unable to generate a preview for this web page, because the following oEmbed / OpenGraph tags could not be found: description, image
That page has an empty description OpenGraph meta tag, so we can’t embed it. It also uses relative URLs for some other OpenGraph tags, like image and url which I’m not sure it’s supported.
Is that an actual entry? The description should be longer, and contain a subset of the actual content on the page, not a placeholder like “SunPy Documentation”.
The description is being ignored because it’s identical to the title. You should be excerpting relevant parts of the content into the description property.