Enable sphinx on servers_client

servers_client is most useful client for testing, but the docstring was
not enabled on the site. So this patch makes it enabled.

Change-Id: I031de923deab74bc0f84cff52f470ab233b7dbba
diff --git a/doc/source/library/service_clients/compute_clients.rst b/doc/source/library/service_clients/compute_clients.rst
new file mode 100644
index 0000000..4ca55d4
--- /dev/null
+++ b/doc/source/library/service_clients/compute_clients.rst
@@ -0,0 +1,7 @@
+.. _servers_client:
+
+Compute Client Usage
+====================
+
+.. automodule:: tempest.lib.services.compute.servers_client
+   :members: