Update changelog for v1.6 release

Signed-off-by: Leonid Kondrashov <leo.kondrashov@gmail.com>

Author: leokondrashov

CHANGELOG.md

@@ -2,6 +2,14 @@
 
 ## [Unreleased]
 
+### Added
+
+### Changed
+
+### Fixed
+
+## v1.6
+
 ### Added
 - Added support for [NVIDIA GPU](https://docs.nvidia.com/datacenter/cloud-native/kubernetes/install-k8s.html) in stock-only setup, with [setup script](./scripts/gpu/setup_nvidia_gpu.sh) and [example](./configs/gpu/gpu-function.yaml) Knative deployment 
 - Upgraded the Firecracker version.  [Vanilla Firecracker snapshots](./docs/snapshots.md) are