all: don't use XXX strings unnecessarily
None of these were "XXX" comments in the sense that the code
cannot be in master, as described in #1959.
Use more realistic examples, other characters like NNN,
or Foo... rather than FooXXX when we mean any object with that prefix.
For #1959.
Signed-off-by: Daniel Martí <mvdan@mvdan.cc>
Change-Id: Iece6ccbed29223ed44911f8fd1ecc622a6d443fc
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1193723
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Paul Jolly <paul@myitcv.io>