Update the usage documentation with recent changes

Cover the "driver" option and more regular expressions. Also explain
which regular expressions are used in which jobs.

Change-Id: Ic5ccb91b603e0e0bdaa51501025b85383d42453b
diff --git a/doc/source/config/with-nova.rst b/doc/source/config/with-nova.rst
index 3537588..67dcc62 100644
--- a/doc/source/config/with-nova.rst
+++ b/doc/source/config/with-nova.rst
@@ -46,6 +46,8 @@
     # Minimum and maximum API versions to test against.
     min_microversion = <min API version as X.Y>
     max_microversion = <max API version as X.Y>
+    # Driver to use for API tests for Queens and newer:
+    driver = fake-hardware
 
     [compute]
     # Configure the bare metal flavor so that the Compute services provisions
diff --git a/doc/source/usage.rst b/doc/source/usage.rst
index 3e3c56e..27b5ebe 100644
--- a/doc/source/usage.rst
+++ b/doc/source/usage.rst
@@ -38,11 +38,20 @@
 
 ``ironic``
     all bare metal tests
+``ironic_tempest_plugin.tests.api``
+    only API tests using fake hardware, without other OpenStack services (these
+    tests are run by jobs starting with ``tempest-dsvm-ironic-functional``)
+``ironic_tempest_plugin.tests.scenario``
+    all integration tests, excluding the API tests with fake hardware (these
+    tests are run by most of the jobs)
 ``ironic_standalone``
     standalone bare metal tests that do not use the Compute service
+    (these tests are run by the job ``ironic-dsvm-standalone``)
 ``InspectorBasicTest``
-    basic introspection tests
+    basic introspection tests (these tests are run by most of the jobs with
+    ``ironic-inspector`` in their name)
 ``InspectorDiscoveryTest``
-    introspection auto-discovery tests
+    introspection auto-discovery tests (these tests are run by the job
+    ``ironic-inspector-tempest-dsvm-discovery`` and require additional set up)
 
 .. _Tempest documentation: https://docs.openstack.org/tempest/latest/run.html