Provide oembed page block documentation

[kimisgold]

While looking into omeka/omeka-s#2161, I realized covering oembed is one hole in our page block documentation. @allanaaa wants to be able to change the url value, but I think that it's not editable due to the information pulled from the url sitting under the advanced options. We should provide some explanation of that interaction, as well as what's intended by the refresh block option.

[allanaaa]

Is this new for 4.1? I know we have had oEmbed for media on items for a while. If so, I'll do this as part of the 4.1 pull request.

[kimisgold]

You're right, I was thinking of the oembed media having been around. The page block is indeed new and included on the 4.1 feature list.

[kimisgold]

I just found it on your task list so I'll close this issue.