add release notes to README.md
add release notes to README.md

NebulousLabs/Sia,johnathanhowell/Sia,mnsl/Sia,Mingling94/Sia,mtlynch/Sia,mtlynch/Sia,ericflo/Sia,ChrisSchinnerl/Sia,rivine/rivine,ChrisSchinnerl/Sia,ericflo/Sia,mharkus/Sia,rivine/rivine,mnsl/Sia,MrStrong/Sia,MrStrong/Sia,mharkus/Sia,kustomzone/Sia,NebulousLabs/Sia