Update rrf.asciidoc (elastic#103078)

typo

(cherry picked from commit 851cab6)

docs/reference/search/rrf.asciidoc

@@ -51,7 +51,7 @@ equal to `1`. Defaults to `60`.
 `window_size`::
 (Optional, integer) This value determines the size of the individual result sets per
 query. A higher value will improve result relevance at the cost of performance. The final
-ranked result set is pruned down to the search request's <<search-size-param, size>.
+ranked result set is pruned down to the search request's <<search-size-param, size>>.
 `window_size` must be greater than or equal to `size` and greater than or equal to `1`.
 Defaults to `100`.