need UI for creating a checkoff #104
Description
What if notes.html contained a URL that the Constellation TA could use to kick off a checkoff? It could include the milestone name and the filename filter, so that it doesn't have to be repeated each time. The URL could lead to a form that asks for the rubric (so that the rubric is included in Constellation at the top of each checkoff page, rather than in Slack). Pressing the button to "create milestone" could set the timestamp on the milestone.