add note on deprecation

bjornregnell · bjornregnell · commit 47eabb66ce51 · 2023-05-10T18:59:14.000+02:00
diff --git a/migration.md b/migration.md
@@ -1,5 +1,7 @@
 # Migration guide Scala 2 -> Scala 3
 
+NOTE: This guide is deprecated and will not be updated, as all Scala 2 code is migrated to Scala 3 in this repo.
+
 ## Currently already completed migrations
 
 * All code in [compendium/examples] has been migrated using `-rewrite`
