Add social image

[fflaten]

Add a social/opengraph image to improve share cards in social media platforms etc.

Which image?
Size: max 1200 × 630 pixels (aspect ratio of 1.91:1)

• https://github.com/pester/Pester/blob/main/images/pester_white_with_text.pdf ?
• Is there a newer blue banner with logo and text?

Can be configured in docusaurus.config.js:

const config = {
 ..
 themeConfig:
 /** @type {import('@docusaurus/preset-classic').ThemeConfig} */
 ({
 metadata: [
 ..
 ],
 // Social image for sharing, sets og:image and twitter:image meta-tags. Path relative to /static folder
 image: 'img/logo.png',

Preview-deployments can be tested using something like: https://www.opengraph.to/u/pester.dev/docs/commands/Should-BeEquivalent