Examples more friendly to share on social networks

[maximlt]

A feature that blogs usually get for free, allowing them to share links on social networks (chats, forums, etc.) that look pretty, with an image, description, etc.

• https://github.com/wpilibsuite/sphinxext-opengraph
• https://github.com/choldgraf/sphinx-social-previews
• Sphinx meta directive https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#html-metadata
• To preview a specific page: https://socialsharepreview.com/

[jbednar]

Good use case for #91 and #475 ! :-)

[maximlt]

Yep, although we'll need to make sure social platforms follow the redirects, to the page that has the opengraph/whatever metadata.