Add documentation.

Change-Id: I8197ec2e52596fa4136f8af9aa93ea06e56d4d0d
diff --git a/setup.cfg b/setup.cfg
new file mode 100644
index 0000000..8a9134b
--- /dev/null
+++ b/setup.cfg
@@ -0,0 +1,4 @@
+[build_sphinx]
+source-dir = doc/source
+build-dir = doc/build
+all_files = 1