[Gameplay} There is a bug with the tooltip for Thunderlord's Decree

When you are creating your mastery tree in the client it shows that ThunderLord's Decree(TD) is a 20 second cooldown. In Game, when you press Tab to open the overview of champions and hold your mouse over the TD image, it shows that it is a 30 second cooldown.

1. open up mastery pages in your profile in the client.
2. scroll over mastery keystone, Thunderlord's Decree, and read a 20 second cooldown.
3. In Game, Press the TAB button and hold.
4. mouse over any of the Thunderlord's Decree icons
5. Read that it states a 30 second cooldown This is visible in every game on every champion/player who is using the Thunderlord's Decree keystone mastery.