Consider using towncrier to create release notes for CMEW #293
Description
When we were working on the v2.11.0 release for ESMValCore, Bouwe mentioned that the Tech Lead Team agreed some time ago to try out towncrier.
towncrier appears to be straightforward to use; we should consider using towncrier to create the release notes for CMEW (for the v0.2.0 release and beyond, since the v0.1.0 milestone contains 195 items and I don't think it would be worth the effort to document all the items for the first release).