add preview tag

Author: tteofili

docs/reference/query-languages/esql/_snippets/lists/search-functions.md

@@ -2,5 +2,5 @@
 * [`MATCH`](../../functions-operators/search-functions.md#esql-match)
 * [`MATCH_PHRASE`](../../functions-operators/search-functions.md#esql-match_phrase)
 * [`QSTR`](../../functions-operators/search-functions.md#esql-qstr)
-* [`SCORE`](../../functions-operators/search-functions.md#esql-score)
+* [preview] [`SCORE`](../../functions-operators/search-functions.md#esql-score)
 % * [preview] [`TERM`](../../functions-operators/search-functions.md#esql-term)