To create this post, you should start in the album on Photos and then share via G+ to the name of your Collection.
Then you also can add some text like this.
You also can create a collection for a dedicated group and such a collection will be not visible on your public G+ page.
So this is a phantastic and versatile way to share, because on Photos itself you only can share albums individually.
The album shown is not a normal holidays series, but just a large bunch of technical pictures for use on forums to explain everything related with having a photocollection at Google.
But if you choose for a public collection, the content of the albums linked-to must be suitable for public viewing and general web searching also.