sharedContent needs an example. It's not clear in what context you would use it. It's not clear if I should use this entity or not, or what for. It's not clear how to use it at all in fact.
Other entities have examples so it seems like a good idea to have one for this.
Suitable example is already available for parent type SocialMediaPosting. Created Pull Request (#998) to make that example appear on the sharedContent page.
So it does! Your commit will make it a bit easier for wallies like me though. Thanks.
Published - see http://schema.org/docs/releases.html