Draft release notes and readme

[Cheetham, Anastasia]

Colin and Jess, I've drafted updates to the README and Release notes files and pushed changes to a branch in my github repo:
	https://github.com/acheetham/infusion/tree/FLUID-4251-readmeReleaseNotes

Do either of you have time to review these? I'll probably hold off on the official pull request until right before code freeze, in case there are last-minute updates to the known issues list, for example, but a general review now would be helpful.

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Anastasia Cheetham     Inclusive Design Research Centre
acheetham at ocad.ca            Inclusive Design Institute
                                        OCAD University