prepare next release (#1536)

Author: jderusse

CHANGELOG.md

@@ -1,6 +1,6 @@
 # Change Log
 
-## NOT RELEASED
+## 2.0.0
 
 ### BC-BREAK
 
@@ -15,6 +15,12 @@
 
 - AWS enhancement: Documentation updates.
 - AWS api-change: This release adds ReturnValuesOnConditionCheckFailure parameter to PutItem, UpdateItem, DeleteItem, ExecuteStatement, BatchExecuteStatement and ExecuteTransaction APIs. When set to ALL_OLD, API returns a copy of the item as it was when a conditional write failed
+- Avoid overriding the exception message with the raw message
+- Use int as the PHP representation of long fields in generated code
+
+### Changed
+
+- Improve parameter type and return type in phpdoc
 
 ## 1.4.0