Khaznad doesn't like books or writing so he doesn't keep an actual log like this, but this is how he will tell the tale of his adventures to his people when he one day returns to them. As such it is as seen from his perspective, very biased, and in draconic.
And thus the other characters in the party doesn't really know any of this, so if the players read this, they got to keep it away from their characters.
D&D 5E Pre-made Adventure: Hoard of the Dragon Queen