release-notes: Add release notes for 0.16.0-beta1

This commit adds the release notes for the Zephyr SDK 0.16.0-beta1
release.

Signed-off-by: Stephanos Ioannidis <[email protected]>

Author: stephanosio

release-notes.md

@@ -1,5 +1,26 @@
 # Notes / Changes in various releases
 
+## Zephyr SDK 0.16.0-beta1
+
+- general:
+
+  * Changed the distribution bundle archive format from `tar.gz` to `tar.xz` for
+    Linux and macOS and from `zip` to `7z` for Windows in order to reduce the
+    download size.
+  * Removed the unused `xtensa-intel_bdw_adsp_zephyr-elf` and
+    `xtensa-intel_byt_adsp_zephyr-elf` toolchain.
+
+- gcc:
+
+  * Added Picolibc and the libstdc++ compiled for it as part of the toolchain
+    in order to allow using the C++ standard library alongside the Picolibc.
+
+- qemu:
+
+  * Added KVM (Kernel-based Virtual Machine) mode support for the AArch64 and
+    x86-64 targets. This allows running the KVM-enabled Zephyr boards such as
+    `qemu_kvm_arm64`.
+
 ## Zephyr SDK 0.15.2
 
 - general: