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

doc/source/library/clients.rst

@@ -16,9 +16,18 @@ service client module from a set of shared parameters.
 The ``ServiceClients`` class provides a convenient way to get access to all
 available service clients initialized with a provided set of credentials.
 
-------------------
-The clients module
-------------------
+-----------------------------
+The clients management module
+-----------------------------
 
 .. automodule:: tempest.lib.services.clients
    :members:
+
+------------------------------
+Compute service client modules
+------------------------------
+
+.. toctree::
+   :maxdepth: 2
+
+   service_clients/compute_clients

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:

tempest/lib/services/compute/servers_client.py

@@ -30,6 +30,8 @@ from tempest.lib.services.compute import base_compute_client
 
 
 class ServersClient(base_compute_client.BaseComputeClient):
+    """Service client for the resource /servers"""
+
     schema_versions_info = [
         {'min': None, 'max': '2.2', 'schema': schema},
         {'min': '2.3', 'max': '2.8', 'schema': schemav23},