Complete descriptive book return links

README.md

@@ -4,11 +4,10 @@ Rivencraft is a clean, incremental port of the ideas and gameplay of
 [Mystcraft Legacy](https://github.com/Mystcraft/Mystcraft-Legacy) to Minecraft
 1.21.1 on NeoForge.
 
-The bootstrap milestone is complete and books/linking is in progress. The
-project currently provides an unwritten Descriptive Book and a functional
-Linking Book with persistent, dimension-aware destinations and safe landing
-checks. Age generation, symbols, instability, and writing mechanics have not
-been ported yet.
+The bootstrap and books/linking milestones are complete. The project currently
+provides functional Linking Books and temporary vanilla-dimension Descriptive
+Book destinations with generated Return Links. Age generation, symbols,
+instability, and writing mechanics have not been ported yet.
 
 ## Linking Book
 
@@ -17,7 +16,7 @@ air. An unbound book opens a screen where it can be named and bound to the
 current location. A bound book opens its destination screen and travels when
 its preview panel is clicked. The destination is stored on the item and
 survives inventory and world saves. Travel only succeeds if the target
-dimension is loaded and a solid, collision-free landing position can be found
+dimension is loaded and a non-fluid, passable landing position can be found
 nearby.
 
 Right-click an empty vanilla lectern with a Rivencraft book to convert it into
@@ -32,6 +31,13 @@ rotating Ponder scene on the left page, backed by the
 destination biome's sky color. The snapshot is visual only; the server
 independently validates every link.
 
+## Descriptive Book
+
+Until generated Ages arrive in Milestone 3, written Descriptive Books resolve
+deterministically to the Overworld, Nether, or End according to their Age UUID.
+The Rivencraft creative tab includes one sample book for each. Linking creates
+a bound Return Link to the exact source position and orientation.
+
 ## Requirements
 
 - A Java 21 JDK