Add new unreleased changelog (#6203)

2.0.0-beta2 is out!

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Author: Manishearth

CHANGELOG.md

@@ -1,5 +1,20 @@
 # Changelog
 
+## Unreleased
+
+- Components
+    - General
+        - ...
+    - ...
+- Data model and providers
+    - General
+        - ...
+    - ...
+- Utils
+    - General
+        - ...
+    - ...
+
 ## icu4x 2.0-beta2
 
 - Components