Deprecate credential config options

This commit deprecates the original configuration options for
providing credentials. This mechanism of providing tempest with
credentials to run with has a lot of drawbacks and has been
superseded by using an accounts.yaml file. It has been planned
for deprecation once we had a periodic/experimental CI job setup
to run with test accounts enabled. Now that this has been done
we can start the deprecation cycle for the old options.

Change-Id: Ia5132c5cb32355d6f26b8acdd92a0e55a2c19f41
diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 3c109b5..1c29de9 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -75,8 +75,9 @@
 To enable and use tenant isolation you only need to configure 2 things:
 
  #. A set of admin credentials with permissions to create users and
-    tenants/projects. This is specified in the identity section with the
-    admin_username, admin_tenant_name, and admin_password options
+    tenants/projects. This is specified in the auth section with the
+    admin_username, admin_tenant_name, admin_domain_name, and admin_password
+    options
  #. To enable tenant_isolation in the auth section with the
     allow_tenant_isolation option.
 
@@ -125,6 +126,9 @@
 
 Non-locking test accounts (aka credentials config options)
 """"""""""""""""""""""""""""""""""""""""""""""""""""""""""
+**Starting in the Liberty release this mechanism was deprecated and will be
+removed in a future release**
+
 When Tempest was refactored to allow for locking test accounts, the original
 non-tenant isolated case was converted to internally work similarly to the
 accounts.yaml file. This mechanism was then called the non-locking test accounts