Add "under construction" text to building details

[martinambrus]

When we show a building that's currently being upgraded, let the player know by providing a big bold text. This way, it will be less confusing as to why there is 5% resources bonus missing somewhere between current level and the next in the Grain Mill while it's undergoing an upgrade.

[Shadowss]

You mean this ?

[martinambrus]

Yeah, I didn't even know they added it to T4 :)

[Shadowss]