add doc for shard

diff --git a/doc/build/reference/ext/horizontal_shard.rst b/doc/build/reference/ext/horizontal_shard.rst
new file mode 100644 (file)
index 0000000..149cf20
--- /dev/null
+++ b/doc/build/reference/ext/horizontal_shard.rst
@@ -0,0 +1,14 @@
+Horizontal Shard
+=================
+
+.. automodule:: sqlalchemy.ext.horizontal_shard
+
+API Documentation
+-----------------
+
+.. autoclass:: ShardedSession
+   :members:
+   
+.. autoclass:: ShardedQuery
+   :members:
+