Update changelog for release v16.1

Author: smuehlst

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Release History
 
+## [v16.1](https://github.com/smuehlst/circle-stdlib/releases/tag/v16.1)
+
+* Synced with [Circle Step 45.2](https://github.com/rsta2/circle/releases/tag/Step45.2).
+* Update mbed TLS to [release v2.28.3](https://github.com/Mbed-TLS/mbedtls/releases/tag/v2.28.3).
+
 ## [v16](https://github.com/smuehlst/circle-stdlib/releases/tag/v16)
 
 * Synced with [Circle Step 45.1](https://github.com/rsta2/circle/releases/tag/Step45.1).