Added changelog entry for I2S/SAI clocks.

Author: mgottschlag

CHANGELOG.md

@@ -36,6 +36,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Add initial DMA support
 - Allow specification of ADC reference voltage in ADC configuraton structure
 - Added support for hardware-based CRC32 functionality
+- Added support for I2S and SAI clocks
 
 ### Fixed
 - Stability fixes related to SD card write