Add 0.2.0 to changelog

@hathach Tested, so making a new release.

Author: dhalbert

changelog.md

@@ -1,5 +1,9 @@
 # Adafruit nRF52 Bootloader Changelog
 
+## 0.2.9
+
+- Fixed incomplete writes on Windows. Upated tinyusb to handle write10 completion, and use it for finalizing dfu process. Will prevent windows error message pop up. This will also give an extra time for flash writing to complete.
+
 ## 0.2.8
 
 - Fixed OTA issue with nrfConnect on iOS