distribute notice as well [skip ci]

python/MANIFEST.in

@@ -1,5 +1,6 @@
 include README.md
 include ../LICENSE.txt
+include ../NOTICE.txt
 
 global-include CMakeLists.txt
 graft pyarrow

python/setup.cfg

@@ -16,7 +16,9 @@
 # under the License.
 
 [metadata]
-license_file = ../LICENSE.txt
+license_files =
+  ../LICENSE.txt
+  ../NOTICE.txt
 
 [build_sphinx]
 source-dir = doc/