Updated CHANGELOG for release v1.6.0 (#317)

Author: bhautikpip

CHANGELOG.md

@@ -1,11 +1,12 @@
-Release v1.6.0 (2021-07-06)
+Release v1.6.0 (2021-07-07)
 ================================
 ### SDK Enhancements
 * AWS SDK v2 instrumentation support [PR #309](https://github.com/aws/aws-xray-sdk-go/pull/309)
 
 ### SDK Bugs
 * Fixed appending to existing gRPC context [PR #308](https://github.com/aws/aws-xray-sdk-go/pull/308)
 * Fixed memory leak issue on fasthttp handler [PR #311](https://github.com/aws/aws-xray-sdk-go/pull/311)
+* Fixed panic issue when segment is not present [PR #316](https://github.com/aws/aws-xray-sdk-go/pull/316)
 
 
 Release v1.5.0 (2021-06-10)