Use Overworld generation for cave and skylands Ages

docs/PORTING.md

@@ -248,6 +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 0.2.16.11 moves Cave and Island/Skylands Ages onto the standard
+Overworld biome, terrain, surface, structure, and feature pipeline. They no
+longer inherit Nether or End generation and dimension behavior.
+
 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
 on a Book Stand. Return Linking Books created inside another Age also retain and