[Tei-council] first draft release notes

Dear all, I made a first draft of the release notes: https://github.com/TEIC/TEI/blob/dev/P5/ReleaseNotes/readme-3.5.0.xml. There are still some TEI issues missing (from #1479 to #1645), which I will add tomorrow. For the Stylesheets release notes: should we add them to the same document? Martina