CHANGELOG.md in google-cloud-bigtable-0.3.1 vs CHANGELOG.md in google-cloud-bigtable-0.4.0

@@ -1,6 +1,12 @@
 # Release History
 
+### 0.4.0 / 2019-05-21
+
+* Add Google::Cloud::Bigtable::VERSION
+* Set gRPC headers to allow maximum message size
+* Fix errors in code sample documentation
+
 ### 0.3.1 / 2019-04-29
 
 * Add AUTHENTICATION.md guide.
 * Update generated documentation.
 * Update generated code examples.