Add changelog entry for 1.0.3
Topic creation improvements, support maintenance window, support
returning VPC peering connection ID.
# Changelog
+## [1.0.3] - 2018-12-11
+Ensure Kafka topic creation succeeds immediately after service creation.
+Support setting service maintenance window.
+Provide cloud provider's VPC peering connection ID (AWS only).
+
## [1.0.2] - 2018-11-21
Support for Prometheus integration and some new user config values.
