Update index.md

Author: LiorKogan

content/commands/json.mget/index.md

@@ -34,6 +34,8 @@ Return the values at `path` from multiple `key` arguments
 
 {{% warning %}}
 When cluster mode is enabled, all specified keys must reside on the same [hash slot](https://redis.io/docs/latest/operate/oss_and_stack/reference/cluster-spec/#key-distribution-model).
+
+When the database has more than one shard and the specified keys reside in different shards, a CROSSSLOT error will not be reported and the results may be partial.
 {{% /warning %}}
 
 [Examples](#examples)