Add http.client transport (#10)

diff --git a/docs/reference/google.auth.transport.rst b/docs/reference/google.auth.transport.rst
new file mode 100644
index 0000000..88b427c
--- /dev/null
+++ b/docs/reference/google.auth.transport.rst
@@ -0,0 +1,8 @@
+google.auth.transport package
+=============================
+
+.. automodule:: google.auth.transport
+    :members:
+    :undoc-members:
+    :show-inheritance:
+