2.0.0-preview.20

[2.0.0-preview.20] - 2020-6-08

• Add warning to advise against use on 2020.1 and above

[2.0.0-preview.19] - 2019-5-31

• Adds yamato ci to the package

[2.0.0-preview.18] - 2019-5-30

• Updates CI script for package promotion