[DOCS] Fix typo

docs/reference/rollup/apis/rollup-api.asciidoc

@@ -146,7 +146,7 @@ Array of <<keyword,keyword family>> and <<number,numeric>> fields to store. If
 you specify a `terms` object, this property is required.
 +
 TIP: Avoid storing high-cardinality fields. High-cardinality fields can greatly
-increase the size of resulting rollup index.
+increase the size of the resulting rollup index.
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