Thumbnails don't show on social media

[boisgera]

• [x] Study the link stuff. In production, all pages end up as index.html files. AFAICT, our links don't have the trailing "/" python the browser add them. Hence, depending on how the user copies the link, the link used in the social media may or may not have a trailing slash. Apparently, twitter is sensitive to this, but not facebook and twitter?
• [x] Some image thumbnails are missing. Test all pages.
• [x] Site name. The site which is displayed is boisgera.github.io. Is it normal (probably?) or could I make it point to boisgera.github.io/itn-web?

Update. Wait ~7 days and

• [ ] Test Linkedin (directly, without url shorteners)
• [ ] Test Twitter
• [ ] Test https://itn-mines-paris.github.io/

[boisgera]

I don't get why say "organisation" doesn't get a thumnail (twitter, facebook), when the site root has one, given that the image metadata is the same!

[boisgera]

OK, so at this stage, wrt https://boisgera.github.io/itn-web/ :

• Signal, Discord, Facebook work out of the box,
• Linkedin has issues, but apparently related to caching only, since testing via tinyurl works,
• Twitter has still issue. They document that they cache for 7 days AND despite their documentation, tinyurl tests won't work at all.