docs/operators: fix a typo
s/are preserved the output/are preserved in the output
@@ -222,7 +222,7 @@ or
both `(label1, label2)` and `(label1, label2,)` are valid syntax.
`without` removes the listed labels from the result vector, while
-all other labels are preserved the output. `by` does the opposite and drops
+all other labels are preserved in the output. `by` does the opposite and drops
labels that are not listed in the `by` clause, even if their label values are
identical between all elements of the vector.
