Numbered field references have been used in the first two examples,
so it's quite reasonable to take the opportunity to introduce a new (and quite useful!) concept.
In addition, this commit makes a few tweaks to the example descriptions, to make them clearer.
Fixes#310
Some files had no newlines, some had 1 newline and some more than 1 newline.
Normalize them all to have only 1 newline at the end of all files.