upgrade guide

Signed-off-by: Edward Welch <[email protected]>

docs/sources/setup/upgrade/_index.md

@@ -186,6 +186,14 @@ Structured Metadata is enabled by default in Loki 3.0, however, it requires your
 
 Automatic stream sharding helps keep the write load of high volume streams balanced across ingesters and helps to avoid hot-spotting. Check out the [operations page](https://grafana.com/docs/loki/latest/operations/automatic-stream-sharding/) for more information
 
+#### More results caching is enabled by default
+
+The TSDB index type has support for caching results for 'stats' and 'volume' queries which are now enabled by default.
+
+'label' and 'series' requests can be cached now too and this is enabled by default.
+
+All of these are cached to the `results_cache` which is configured in the `query_range` config section.  By default, an in memory cache is used.
+
 #### Write dedupe cache is deprecated
 Write dedupe cache is deprecated because it not required by the newer single store indexes ([TSDB]({{< relref "../../operations/storage/tsdb" >}}) and [boltdb-shipper]({{< relref "../../operations/storage/boltdb-shipper" >}})).
 If you using a [legacy index type]({{< relref "../../storage#index-storage" >}}), consider migrating to TSDB (recommended).