Merge pull request adafruit#253 from adafruit/add-softdevice-uf2

add converted softdevice uf2 for easy recovery

Merge pull request adafruit#252 from adafruit/separate-release-artifact

Separate release artifact

Update changelog.md

Update changelog.md

Update changelog.md

update changelog

Update changelog.md

upload update uf2 separately in release

Merge pull request adafruit#185 from adafruit/upload-artifacts

Prepare for release

add changelog for release