[Feature Request] Improve ReleaseNotes Generation

ReleaseNotes are now supposed to contain prerelease versions (e.g. 3.0.0-alpha.1). The PreReleaseNotes task can be used for this, but doesn't handle it completely. If there is already a version with the same SemVer, the new prerelease tag will be put as the new header of the exisiting sections.

And this should be improved, by having the task create a new section.