add howto video

README.md

...-video/2019-11-19_cf-explainers_l0-01-add-and-connect.mp4

...9-11-19_cf-explainers_l0-02-change-states-and-operate.mp4

...video/2019-11-19_cf-explainers_l0-03-save-and-restore.mp4

doc/basics-video/2019-11-19_cf-explainers_l1-01-dive-in.mp4

...basics-video/2019-11-19_cf-explainers_l1-02-add-stuff.mp4

...ics-video/2019-11-19_cf-explainers_l1-03-save-restore.mp4

save/systems/demo-david.json

save/systems/demo-inversion.json

save/systems/demo-l1-errlight.json