internal/core/adt: fix typo
internal/core/adt: fix typo

Closes #959
https://github.com/cuelang/cue/pull/959

GitOrigin-RevId: d568806b56d4179e3a5553173e1611224c2458c7
Change-Id: I7563f76aa4704e1f3de4d2aebef9139877c662bb
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9801
Reviewed-by: CUE cueckoo <0f32a827c9a5f00281f936ac78b5ef3ba80a954c@gmail.com>
Reviewed-by: Marcel van Lohuizen <a22d082192f3ccf984644a4f482781f4c2d65180@golang.org>

cuelang/cue