Add markup for sharing links on social media sites

Comms often have to create and upload separate images when sharing links on Facebook, Twitter and Mastodon as our current blog posts don't generate link previews on the timeline.

To reduce this effort, could we add the appropriate share metatags for the following platforms:

• Facebook
• Twitter
• Mastodon (it seems this uses Opengraph too, so no further action may be necessary)

Full-sized cards featuring the blog post's title, description and banner image would be great, please.