[skip ci] add notes to client.go (#12542)

Signed-off-by: Nzilliz <zilliz@zillizdeMacBook-Pro.local>
Co-authored-by: Nzilliz <zilliz@zillizdeMacBook-Pro.local>

internal/distributed/proxy/client/client.go

@@ -249,6 +249,7 @@ func (c *Client) GetStatisticsChannel(ctx context.Context) (*milvuspb.StringResp
 	return ret.(*milvuspb.StringResponse), err
 }
 
+// InvalidateCollectionMetaCache invalidate collection meta cache
 func (c *Client) InvalidateCollectionMetaCache(ctx context.Context, req *proxypb.InvalidateCollMetaCacheRequest) (*commonpb.Status, error) {
 	ret, err := c.recall(func() (interface{}, error) {
 		client, err := c.getGrpcClient()