Release Healer Man 0.1.21

README.md

@@ -41,6 +41,10 @@ npm test
 npm run build
 ```
 
+Boss-mechanic and dungeon-event extension points, telegraph rules, checkpoint
+behavior, test workflow, and the explicit source-gap ledger are documented in
+[`ENCOUNTER_AUTHORING.md`](ENCOUNTER_AUTHORING.md).
+
 ## Content downloads
 
 Production browser and Android builds ship a compact required set: the game