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