Update release notes for 1.2.0

[ssnn]

Did you forget to update the Release notes in `NEWS.md`? I was checking if readthedocs had the 1.2.0 documentation, and noticed https://dowser.readthedocs.io/en/latest/news/ and https://dowser.readthedocs.io/en/1.2.0/news/ didn’t show release notes for 1.2.0.

[Kenneth Hoehn]

Fixed https://bitbucket.org/kleinstein/dowser/commits/179771ef70ca77d3852e37c7d5d3af2b53e89c57