Ability to define a main image per article

[jflheureux]

The Coveo Community team is indexing this blog and surfaces the articles in a search page. The result template includes an image for each article.

They used random placeholder images for the moment.

The idea would be to allow to define a main image for each article. It could be defined in the front matter of each markdown file.

We should put its URL in the og:image meta tag in the head of the pages and also put the relevant sizes in the og:image:width and og:image:height tags.

At the same time, we should update the twitter:image meta tag value.

Then, the Coveo Community team would be able to index that image URL and use it in their result templates.