Import documentation tweaks (rebased onto develop)



This is the same as gh-917 but rebased onto develop.

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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 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!

Edit: Removed a commit which, "* it updates the included help". This include will be fixed in a separate PR.