docs(reference): document the total property in response from /v1/load (#7042)

Author: hassankhan

docs/docs-new/pages/product/apis-integrations/rest-api/query-format.mdx

@@ -37,6 +37,8 @@ A Query has the following properties:
 - `limit`: A row limit for your query. The default value is `10000`. The maximum
   allowed limit is `50000`. If you'd like to request more rows than the maximum
   allowed limit, consider using [pagination][ref-recipe-pagination].
+- `total`: If set to `true`, Cube will return the total number of rows for a
+  query. The default value is `false`.
 - `offset`: The number of initial rows to be skipped for your query. The default
   value is `0`.
 - `order`: An object, where the keys are measures or dimensions to order by and

docs/docs-new/pages/reference/rest-api.mdx

@@ -24,6 +24,8 @@ Response
   - `title` - Human readable title from the data model.
   - `shortTitle` - Short title for visualization usage (ex. chart overlay)
   - `type` - Data type
+- `total` - The total number of rows returned for the query. Useful for
+  paginating results.
 
 Example request: