A bunch of editorial stuff

The abbreviated title was naff (technical term, that).

Nikos rightly noted that the important stuff was somewhat buried in the intro.  I fixed that by adding a header.

Nikos also notes that we don't recommend an alternative.  I thought that was obvious, but added text anyway.

I thought that copy-paste from AppxE of 5246 was fine, but felt motivated to reword it a little.