Embargo: title of embargo document is visible for regular editors in activity stream

A non-embargo CMS user sees activities on Embargo documents in the dashboard.

Page https://onehippo-forge.github.io/embargo/usage.html documents this under "Known limitations":

• History plugin may show some embargo related information. The Hippo log and version history do not take into account the embargo status of a document.

Let's see if we can fix that.