We often send links to our clients to view specific documents within our support community, like this one:
https://community.pubmatic.com/display/PA/Bid+Response+Objects+and+Parameters
Many systems (Facebook, Twitter, Slack), display a preview of the link for users, and very often, the preview will contain a random image pulled from the document's attached images. Equally often, the chosen image makes absolutely no sense in the context of the document's title/brief intro text. For example (from a document link pasted into Slack):

The secondary problem is that the text description of the document is a sentence fragment that is an excerpt embedded in the doc so the text can be used multiple places. It also makes absolutely no sense in this context. Why is Confluence favoring the excerpt for the preview over the first paragraph of the document, which intros the document's topic?
So my questions is: how can we explicitly set the image and description text that will be shown for a forwarded link, or disable the preview altogether? Thanks.