[skip ci]Add GetCollectionStatisticsRequest in chap05_proxy.md (#9124)

Signed-off-by: Nruiyi.jiang <ruiyi.jiang@zilliz.com>

docs/developer_guides/chap05_proxy.md

@@ -171,7 +171,15 @@ type DescribeCollectionRequest struct {
 
 See _Master API_ for detailed definitions.
 
-- _GetCollectionStatistics_
+- _GetCollectionStatisticsRequest_
+
+```go
+type GetCollectionStatisticsRequest struct {
+	Base            *commonpb.MsgBase
+	DbName          string
+	CollectionName  string
+}
+```
 
 See _Master API_ for detailed definitions.