How to enable the dota2 ingame guides

I've recently subscribed to a dota2 guide via the steam workshop, but nothing has changed so far in the game.

Are the guides perhaps something that only show up in the test build or do I need to activate some setting?

Guide in question: http://steamcommunity.com/sharedfiles/filedetails/?id=128795071


You just have to click on the book on the top left corner and select your guide enter image description here