Add support for authors around how to teach well

[rosemm]

Expert knowledge does not guarantee effective teaching, or make it easy. Teaching technical material well is hard work, and requires time and thought. Right now nothing in our author guidelines directly addresses our standards for pedagogy broadly -- we address how to craft learning objectives, and how to use formative assessment, but there's no overall guidance on how to teach well.

In jira: https://pm.arcus.chop.edu/browse/EDU-1382