Normalize the gnocchiclient docs entry

For now, gnocchiclient has been added in the global-requirements, we
should add gnocchiclient in test-requirements.txt and normalize the docs
entry.

Change-Id: Ide5d8262e7f7c5b1ca304fa72893ccfbf16d8ec1

Author: liusheng

doc/source/plugin-commands.rst

@@ -33,10 +33,10 @@ designate
 .. list-plugins:: openstack.dns.v1
    :detailed:
 
-.. gnocchi
-.. # gnocchiclient is not in global-requirements
-.. # list-plugins:: openstack.metric.v1
-.. #  :detailed:
+gnocchi
+-------
+.. list-plugins:: openstack.metric.v1
+   :detailed:
 
 heat
 ----

doc/source/plugins.rst

@@ -22,7 +22,7 @@ OpenStackClient.
 The following is a list of projects that are an OpenStackClient plugin.
 
 - aodhclient
-- gnocchiclient\*\*
+- gnocchiclient
 - python-barbicanclient
 - python-congressclient
 - python-designateclient

test-requirements.txt

@@ -24,6 +24,7 @@ wrapt>=1.7.0 # BSD License
 
 # Install these to generate sphinx autodocs
 aodhclient>=0.7.0 # Apache-2.0
+gnocchiclient>=2.7.0  # Apache-2.0
 python-barbicanclient>=4.0.0 # Apache-2.0
 python-congressclient<2000,>=1.3.0 # Apache-2.0
 python-designateclient>=1.5.0 # Apache-2.0