ChangeLog.md: bump revision to prepare for beta
diff --git a/ChangeLog.md b/ChangeLog.md
index 5e385bb..650199f 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -1,5 +1,5 @@
-2.0 pre-beta
-============
+1.5.90 (2.0 beta1)
+==================
 
 ### Significant changes relative to 1.5.3: