Initial draft for m2 version history

--no-rebase

Initial draft to add m2 to the OMERO version history, could do with @qidane @jburel and @joshmoore looking over it and suggesting additions/modifications - I skimmed PRs but wasn't entirely sure what was most relevant for developers.
I think the plan is to get this out asap but we certainly could add doc links once we have them (although Model doc links would need to URLs rather than internal links).