Unmentioned are:
- Special sequences such as \n.
- Which characters need to be escaped in which kind of quotes.
- What happens if you escape a character that doesn't need escaping.
- Interpolation of arrays.
- Non-interpolation of hashes, globs and code.
- Special variables affecting interpolation, such as $, (and maybe only $,).
- How to interpolate expressions using "@{[ expr ]}"
- <<marker vs <<"marker" vs <<'marker'.
I'm not saying that any of these things should be mentioned, just that you should consider whether they should be mentioned or not.