update change.log to reflect 2.0 and 2.1 spec changes
update change.log to reflect 2.0 and 2.1 spec changes

Signed-off-by: Yushan Lin <f974adf9cef15b0cb163c1734d1de83159320d41@ibm.com>

Channyboy/microprofile-metrics,Channyboy/microprofile-metrics