Use uniform Overworld skylands generation

docs/PORTING.md

@@ -248,9 +248,10 @@ honor the server's loaded data packs. Automated coverage also verifies that a
 live Age's seed equals its immutable saved definition; Dynamic Dimensions
 derives both from the Overworld seed and the Age dimension identifier.
 
-Version 0.2.16.12 gives Cave and Island/Skylands Ages Overworld biomes, sky,
-weather, lighting, and day/night behavior while retaining their distinct
-terrain density: enclosed Nether-shaped caves and End-shaped floating islands.
+Version 0.2.16.13 gives Cave and Island/Skylands Ages Overworld biomes, sky,
+weather, lighting, and day/night behavior while retaining distinct terrain.
+Caves remain enclosed. Skylands use Minecraft's uniform floating-island noise
+and Overworld-like surfaces without the End's central dragon island.
 
 Version 0.2.14.0 restores the legacy Linking and Descriptive Book artwork for
 inventory items and gives each book its matching open-book texture when placed