[release] Prepare changelog for 2.1.0-dev.0.0
TBR=whesse@google.com
Change-Id: I3909ce29bba429a6fad9238faa11efecd73f6fb9
Reviewed-on: https://dart-review.googlesource.com/69100
Reviewed-by: Alexander Thomas <athom@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4ebca93..db24696 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,20 @@
-## 2.1.0
+## 2.1.0-dev.XX.0
+(Add new changes here, and they will be copied to the change section for the
+ next dev version)
+
+### Language
+
+### Dart VM
+
+### Tool Changes
+
+#### Pub
+
+#### Other Tools
+
+### Core library changes
+
+## 2.1.0-dev.0.0
### Tool Changes
