Complete scaled biome distributions

docs/PORTING.md

@@ -345,6 +345,11 @@ Age-seeded biomes and softly bounded seeded regions. Tiny begins at Legacy's
 smallest 16-block nominal scale; the serializable biome source retains its
 seed, selected biomes, and scale across Age reloads.
 
+Version 0.2.25.0 completes the scaled biome distributions. Small, Medium,
+Large, and Huge reuse Tiny's seeded, softly bounded regions at nominal widths
+of 32, 64, 128, and 256 blocks. Every size selects three deterministic biomes
+and serializes the selection, Age seed, and scale with the runtime dimension.
+
 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