Exclude 'keystone_tempest_plugin' in doc build
Exclude 'keystone_tempest_plugin' in doc build

When building keystone docs, autodoc goes through all of
the project in order to auto-generate api docs. When going
through 'keystone_tempest_plugin', there are currently 6
warnings that are emitted due to issues with duplicate
option errors. These errors seem to be related to duplicate
named options between tempest and oslo.config, rather than
keystone.

Due to these warnings, there are already multiple issues with
the api page [1] not rendering everything.

This change adds 'keystone_tempest_plugin' to the exclusion list
for autodoc and as a result, removes the 6 warnings from doc building
since 'keystone_tempest_plugin' will no longer be auto-generated
with incomplete info.

[1] http://docs.openstack.org/developer/keystone/api/keystone_tempest_plugin.html

Change-Id: Icb5c518b2f1409e2e9580b14ba1ae0e44995a73c
Co-Authored-By: Tin Lam <7dced2b40d40adef244c7d1ddeefda31a0ae61f9@gmail.com>
Partial-Bug: #1602422

openstack/keystone,rajalokan/keystone,mahak/keystone,mahak/keystone,openstack/keystone,rajalokan/keystone,rajalokan/keystone,ilay09/keystone,ilay09/keystone,mahak/keystone,ilay09/keystone,openstack/keystone