[asf] add notice file (#12)

diff --git a/NOTICE.txt b/NOTICE.txt
new file mode 100644
index 0000000..4be4efd
--- /dev/null
+++ b/NOTICE.txt
@@ -0,0 +1,6 @@
+Apache Doris StreamLoader
+Copyright 2024 The Apache Software Foundation
+
+This product includes software developed at
+The Apache Software Foundation (http://www.apache.org/).
+