Please accept my apologies if this is too trivial a pull request, but I was today reading the documentation in this file, and I had to read the introduction a few times before I understood what it meant.
There should be no comma in front of that (while there should be comma in front of which).
It's non-empty, not none empty
Regarding single-element result, that's a compound adjective, so here I've followed Strunk & White and added a hyphen.
Please accept my apologies if this is too trivial a pull request, but I was today reading the documentation in this file, and I had to read the introduction a few times before I understood what it meant.