Adds a full example of devstack local.conf

The current instructions of "How to use with devstack" should be more
accurate and consistent with instructions of "Install Trove in DevStack"
page[1].

Adding a trove-dashboard plugin line to local.conf which is shown in "
Install Trove in DevStack" page[1] is not enough. Because you will see
the following error after executing "./stack.sh"::

    ++ /opt/stack/trove-dashboard/devstack/plugin.sh:source:34 :   configure_trove_dashboard
    ++ /opt/stack/trove-dashboard/devstack/plugin.sh:configure_trove_dashboard:10 :   cp -a /opt/stack/trove-dashboard/trove_dashboard/enabled/_1710_database_panel_group.py /opt/stack/trove-dashboard/trove_dashboard/enabled/_1720_project_databases_panel.py /opt/stack/trove-dashboard/trove_dashboard/enabled/_1730_project_database_backups_panel.py /opt/stack/trove-dashboard/trove_dashboard/enabled/_1731_project_database_backups_panel.py /opt/stack/trove-dashboard/trove_dashboard/enabled/_1740_project_database_clusters_panel.py /opt/stack/trove-dashboard/trove_dashboard/enabled/_1760_project_database_configurations_panel.py /opt/stack/trove-dashboard/trove_dashboard/enabled/__init__.py /opt/stack/horizon/openstack_dashboard/local/enabled/
    cp: target '/opt/stack/horizon/openstack_dashboard/local/enabled/' is not a directory
    + /opt/stack/trove-dashboard/devstack/plugin.sh:configure_trove_dashboard:1 :   exit_trap

I propose to add a full example of local.conf that includes trove
plugin and horizon service. Devstack is a tool to make an all-in-one
OpenStack environment for development. It is natural that trove and
trove-dashboard will be installed together. By doing so, developers
can easily make an all-in-one trove-dashboard environment.

1: https://docs.openstack.org/trove/latest/install/install-devstack.html

Story: 2007462
Task: 39142
Signed-off-by: Hirotaka Wakabayashi <hiwkby@yahoo.com>
Change-Id: Id05348b4ba7cf55f21297933ac60f5b7fcc2edbd

README.rst

@@ -20,6 +20,74 @@ Add the following to your devstack ``local.conf`` file::
 
     enable_plugin trove-dashboard https://opendev.org/openstack/trove-dashboard
 
+Here is a full example of devstack ``local.conf`` file that includes the trove plugin::
+
+    [[local|localrc]]
+    RECLONE=False
+    HOST_IP=<your-host-ip-here>
+
+    enable_plugin trove https://opendev.org/openstack/trove
+    enable_plugin trove-dashboard https://opendev.org/openstack/trove-dashboard
+
+    LIBS_FROM_GIT+=,python-troveclient
+    DATABASE_PASSWORD=password
+    ADMIN_PASSWORD=password
+    SERVICE_PASSWORD=password
+    SERVICE_TOKEN=password
+    RABBIT_PASSWORD=password
+    LOGFILE=$DEST/logs/stack.sh.log
+    VERBOSE=True
+    LOG_COLOR=False
+    LOGDAYS=1
+
+    IPV4_ADDRS_SAFE_TO_USE=10.111.0.0/26
+    FIXED_RANGE=10.111.0.0/26
+    NETWORK_GATEWAY=10.111.0.1
+    FLOATING_RANGE=172.30.5.0/24
+    PUBLIC_NETWORK_GATEWAY=172.30.5.1
+
+    # Pre-requisites
+    ENABLED_SERVICES=rabbit,mysql,key
+
+    # Horizon
+    enable_service horizon
+
+    # Nova
+    enable_service n-api
+    enable_service n-cpu
+    enable_service n-cond
+    enable_service n-sch
+    enable_service n-api-meta
+    enable_service placement-api
+    enable_service placement-client
+
+    # Glance
+    enable_service g-api
+    enable_service g-reg
+
+    # Cinder
+    enable_service cinder
+    enable_service c-api
+    enable_service c-vol
+    enable_service c-sch
+
+    # Neutron
+    enable_service q-svc
+    enable_service q-agt
+    enable_service q-dhcp
+    enable_service q-l3
+    enable_service q-meta
+
+    # enable DVR
+    Q_PLUGIN=ml2
+    Q_ML2_TENANT_NETWORK_TYPE=vxlan
+    Q_DVR_MODE=legacy
+
+    # Swift
+    ENABLED_SERVICES+=,swift
+    SWIFT_HASH=66a3d6b56c1f479c8b4e70ab5c2000f5
+    SWIFT_REPLICAS=1
+
 
 To run unit tests:
 ------------------