Add missing bus documentation in index and fix build warning

doc/ref/index.rst

@@ -17,4 +17,5 @@ API Reference
     sendmail
     filestore
     cache
+    bus
     tests

doc/topics/index.rst

@@ -15,7 +15,7 @@ Introduction to all the key parts of trytond:
     logs
     start_server
     models/index
-    backend-types
+    backend_types
     models/fields_default_value
     models/fields_on_change
     domain
@@ -30,6 +30,7 @@ Introduction to all the key parts of trytond:
     rpc
     task_queue
     user_application
+    bus
     modules/index
     translation
     testing

doc/topics/task_queue.rst

@@ -1,4 +1,4 @@
-.. _topics-task-queue
+.. _topics-task-queue:
 
 ==========
 Task Queue
@@ -42,6 +42,8 @@ Example:
 
 .. highlight:: python
 
+::
+
     from trytond.model import Model
 
     class MyModel(Model):