docs: update changelog for 21.05

Improve lacrosse decoders with sanity checks

Doc update changelog for 20.02

Added 'unique' to example flex decoders (merbanan#1138)

Add Changelog

Touch up waveman code style, add missing time field

Add support for another Fine Offset sensor

Merge pull request merbanan#329 from panarom/master

add missing quhwa.c reference