[skip ci] Add comment for CreatePartition (#11513)

Signed-off-by: Ndragondriver <jiquan.long@zilliz.com>

internal/proxy/impl.go

@@ -560,6 +560,7 @@ func (node *Proxy) ShowCollections(ctx context.Context, request *milvuspb.ShowCo
 	return sct.result, nil
 }
 
+// CreatePartition create a partition in specific collection.
 func (node *Proxy) CreatePartition(ctx context.Context, request *milvuspb.CreatePartitionRequest) (*commonpb.Status, error) {
 	if !node.checkHealthy() {
 		return unhealthyStatus(), nil