Fix warnings in docstrings

When generating the docs some warnings were generated.

Also, configure doc build so that if there are warnings, the
build will fail.

Change-Id: I7e10499294cf1f06f766cbff392e9de32ea48e5a

oslo_db/options.py

@@ -152,9 +152,9 @@ def set_defaults(conf, connection=None, sqlite_db=None,
 
     :keyword connection: SQL connection string.
         Valid SQLite URL forms are:
-          * sqlite:///:memory: (or, sqlite://)
-          * sqlite:///relative/path/to/file.db
-          * sqlite:////absolute/path/to/file.db
+        * sqlite:///:memory: (or, sqlite://)
+        * sqlite:///relative/path/to/file.db
+        * sqlite:////absolute/path/to/file.db
     :type connection: str
 
     :keyword sqlite_db: path to SQLite database file.

oslo_db/sqlalchemy/enginefacade.py

@@ -842,7 +842,6 @@ class LegacyEngineFacade(object):
     """A helper class for removing of global engine instances from oslo.db.
 
     .. deprecated::
-
         EngineFacade is deprecated.  Please use
         oslo.db.sqlalchemy.enginefacade for new development.
 

oslo_db/sqlalchemy/test_migrations.py

@@ -166,7 +166,7 @@ class WalkVersionsMixin(object):
 
             If we have ordered migrations 123abc, 456def, 789ghi and we run
             upgrading with the `snake_walk` argument set to `True`, the
-            migrations will be applied in the following order:
+            migrations will be applied in the following order::
 
                 `123abc => 456def => 123abc =>
                  456def => 789ghi => 456def => 789ghi`

setup.cfg

@@ -60,9 +60,7 @@ fixtures =
   testscenarios>=0.4
 
 [pbr]
-# NOTE(viktors): uncomment ``warnerrors`` line, when setup.cfg we then
-# want to treat sphinx warnings as errors
-# warnerrors = True
+warnerrors = True
 autodoc_index_modules = True
 autodoc_exclude_modules =
    oslo_db.tests.*