Create devstack/example.local.conf and include it in the docs

It's convenient to have a downloadable example of local.conf.
This change extracts the example from the contributing documentation.

Also removes the noop variable.

Change-Id: I18a7f9969a9820fa8c736dede5f39c70f9c85b6a

CONTRIBUTING.rst

@@ -86,35 +86,8 @@ components. There is a plugin for installing **ironic-inspector** on DevStack.
 Example local.conf
 ------------------
 
-::
+.. literalinclude:: ../../devstack/example.local.conf
 
-    [[local|localrc]]
-    enable_service ironic ir-api ir-cond
-    disable_service n-net n-novnc
-    enable_service neutron q-svc q-agt q-dhcp q-l3 q-meta
-    enable_service s-proxy s-object s-container s-account
-    disable_service heat h-api h-api-cfn h-api-cw h-eng
-    disable_service cinder c-sch c-api c-vol
-
-    enable_plugin ironic https://github.com/openstack/ironic
-    enable_plugin ironic-inspector https://github.com/openstack/ironic-inspector
-
-    IRONIC_BAREMETAL_BASIC_OPS=True
-    IRONIC_VM_COUNT=2
-    IRONIC_VM_SPECS_RAM=1024
-
-    IRONIC_DEPLOY_DRIVER_ISCSI_WITH_IPA=True
-    IRONIC_BUILD_DEPLOY_RAMDISK=False
-    IRONIC_INSPECTOR_BUILD_RAMDISK=False
-
-    VIRT_DRIVER=ironic
-
-    LOGDAYS=1
-    LOGFILE=~/logs/stack.sh.log
-    SCREEN_LOGDIR=~/logs/screen
-
-    DEFAULT_INSTANCE_TYPE=baremetal
-    TEMPEST_ALLOW_TENANT_ISOLATION=False
 
 Notes
 -----

devstack/example.local.conf

@@ -0,0 +1,26 @@
+[[local|localrc]]
+enable_service ironic ir-api ir-cond
+disable_service n-net n-novnc
+enable_service neutron q-svc q-agt q-dhcp q-l3 q-meta
+enable_service s-proxy s-object s-container s-account
+disable_service heat h-api h-api-cfn h-api-cw h-eng
+disable_service cinder c-sch c-api c-vol
+
+enable_plugin ironic https://github.com/openstack/ironic
+enable_plugin ironic-inspector https://github.com/openstack/ironic-inspector
+
+IRONIC_BAREMETAL_BASIC_OPS=True
+IRONIC_VM_COUNT=2
+IRONIC_VM_SPECS_RAM=1024
+
+IRONIC_BUILD_DEPLOY_RAMDISK=False
+IRONIC_INSPECTOR_BUILD_RAMDISK=False
+
+VIRT_DRIVER=ironic
+
+LOGDAYS=1
+LOGFILE=~/logs/stack.sh.log
+SCREEN_LOGDIR=~/logs/screen
+
+DEFAULT_INSTANCE_TYPE=baremetal
+TEMPEST_ALLOW_TENANT_ISOLATION=False