Documentation about Externally referenced

While testing out 4.11 :
I got tons of : [ObjectName] : Externally referenced
And a link to : http://docs.unrealengine.com/latest/INT/Shared/Editor/MapErrors/index.html?utm_source=editor&utm_medium=docs&utm_campaign=msg_log
But just this error ([ObjectName] : Externally referenced)
has only the title, but no description about what to do to fix this.

Please update the documentation.

Same here…only got 5 of them now, but also wondering what it might mean.