External API user must create at least 2 sitelinks per merchant deployment

Please validate that external api user has provided a minimum of 2 sitelinks. In the UI,

We only WARN the user that the search engine will not display less than 2 sitelinks. We should only throw a warning to the external api user, not an error.

"A minimum of 2 sitelinks must be provided before the search engine will display any sitelinks with ads."

This also needs to be reflected in the documentation.