Configure descriptive book return links

docs/PORTING.md

@@ -168,6 +168,12 @@ End destinations instead of their inherited Overworld biome sky tint.
 Version 0.2.6 expands destination snapshots to a 32-by-32-by-32 cube while
 keeping the existing target-centered Ponder camera position.
 
+Version 0.2.7 persists each Age's first successful visit and creates its
+Return Link only for that initial arrival.
+
+Version 0.2.8 makes Return Link creation a server setting: `ON_CREATION`
+(default), `ALWAYS`, or `DISABLED`.
+
 The preview code is separated behind a renderer interface and uses an isolated
 Ponder level populated from server-authoritative destination snapshots.