prosemirror track changes demo

demo: how to add a "track changes" feature to prosemirror

building

git clone --depth=1 https://github.com/milahu/prosemirror-track-changes-demo
cd prosemirror-track-changes-demo
pnpm install
./install-fiduswriter.sh
npm run build
npm run serve

related

• fiduswriter/fiduswriter#1142
• nytimes/prosemirror-change-tracking-prototype#2