[2021] RU cv what difference from t6 to t8

Some XP grind was moved off of the Tier 4 CV, to help newer players finish working on thier Tier 4 CVs faster. That way they can move up to Tier 6 where the AA is stronger, but they can keep learning their CV line after having learned the basics in Tier 4.

The grind from Tier 8 to Tier 10 is quite large. It can be rough, but considering the grind needed for a Surface Ship going from Tier 8 to 9, and then up again to 10... it's rough, but doable.