Fix a typo in migration notice for upgrade anims

Author: Starkku

docs/Whats-New.md

@@ -12,7 +12,7 @@ You can use the migration utility (can be found on [Phobos supplementaries repo]
 
 - `Vertical=true` projectiles no longer move horizontally if fired by aircraft by default. To re-enable this behaviour set `Vertical.AircraftFix=false` on the projectile.
 - Weapons with `Airstrike=true` on Warhead will now check target eligibility for airstrikes regardless of weapon slot. Use `AirstrikeTargets=all` on `Primary` airstrike weapon Warhead to restore previous behaviour.
-- `PowersUpNAnim` is now used instead of the upgrade building's image file for upgrade animation if set. Note that displaying a damaged version will still require setting `PowerUpXDamagedAnim` explicitly in all cases, as the fallback to upgrade building image does not extend to it, nor would it be safe to add. `PowersUpToLevel=-1` upgrades still do not work correctly `PowersUpNAnim` and such buildings should forgo using explicit upgrade animations.
+- `PowerUpNAnim` is now used instead of the upgrade building's image file for upgrade animation if set. Note that displaying a damaged version will still require setting `PowerUpNDamagedAnim` explicitly in all cases, as the fallback to upgrade building image does not extend to it, nor would it be safe to add. `PowersUpToLevel=-1` upgrades still do not work correctly `PowerUpNAnim` and such buildings should forgo using explicit upgrade animations.
 - `[CrateRules] -> FreeMCV` now controls whether or not player is forced to receive unit from `[General] -> BaseUnit` from goodie crate if they own no buildings or any existing `[General] -> BaseUnit` vehicles and own more than `[CrateRules] -> FreeMCV.CreditsThreshold` (defaults to 1500) credits.
 - Translucent RLE SHPs will now be drawn using a more precise and performant algorithm that has no green tint and banding. Can be disabled with `rulesmd.ini -> [General] -> FixTransparencyBlitters=no`.
 - Iron Curtain status is now preserved by default when converting between TechnoTypes via `DeploysInto` / `UndeploysInto`. This behavior can be turned off per-TechnoType and global basis using `[TechnoType]/[CombatDamage] -> IronCurtain.KeptOnDeploy=no`.