Update Let example in docs

src/content/doc-surrealql/statements/select.mdx

@@ -200,8 +200,13 @@ More info on the `$parent` parameter in the second example can be seen on [the p
 
 ```surql
 -- Store the subquery result in a variable and query that result.
-LET $history = SELECT * FROM events WHERE type = 'activity' LIMIT 5;
-SELECT * from $history;
+LET $avg_price = (
+	SELECT math::mean(price) AS avg_price FROM product GROUP ALL
+	).avg_price;
+
+-- Find the name of the product where the price is higher than the avg price
+SELECT name from product
+WHERE [price] > $avg_price;
 
 -- Use the parent instance's field in a subquery (predefined variable)
 SELECT *, (SELECT * FROM events WHERE host == $parent.id) AS hosted_events FROM user;