Import documentation tweaks

This PR tweaks the sysadmin cli import docs in a few ways:
 * it changes the wording to reflect that the advanced import help is no longer hidden, but was
 * it fixes the rendering of a double dash
 * it updates the included help
 * it reorders two pages. Although a minor point on the website in the PDF docs having the scenarios follow the introduction of in-place import makes more sense when reading linearly.

This description contains more text than the PR!