Add 2.1.3 to CHANGELOG.md (#967)

Author: Adrian Clay

CHANGELOG.md

@@ -25,6 +25,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * When mapping `Immunizations` which contain a `NOPAT` `meta.security` tag, the resultant XML for that resource
   will contain a `NOPAT` `confidentialityCode` element.
 
+## [2.1.3] - 2014-10-25
+
 ### Fixed
 
 * Fix a malformed XML GP2GP message created when mapping a `MedicationRequest` with `intent` of `plan` and is stopped,