[HelpHub] Overhaul Pinterest embed

[estelaris]

Article: https://wordpress.org/documentation/article/pinterest-embed/

Review full article, follow steps from the [HelpHub] Overhauling blocks articles - READ FIRST
#2126

Open issues

• [HelpHub] Broken and missing screenshots (mostly block pages) #1649

[github-actions]

Heads up @WordPress/docs-issues-coordinators, we have a new issue open. Time to use 'em labels.