Cleanup messages doc

Author: Pierre-Sassoulas

doc/user_guide/messages/index.rst

@@ -3,9 +3,29 @@
 Messages
 ========
 
+Pylint can emit various messages. These are categorized according
+to categories corresponding to bit-encoded exit codes:
+
+* Fatal  :ref:`Fatal` (1)
+* Error :ref:`Error` (2)
+* Warning :ref:`Warning` (4)
+* Convention :ref:`Convention` (8)
+* Refactor :ref:`Refactor` (16)
+* Information :ref:`Information` (NA)
+
+A list of these messages can be found in :ref:`messages-list`
+
+Disabling messages
+==================
+
+``pylint`` has an advanced message control for its checks, offering the ability
+to enable / disable a message either from the command line or from the configuration
+file, as well as from the code itself.
+
+For more detail see :ref:`messages_control`
+
 .. toctree::
   :maxdepth: 1
 
-  messages_introduction.rst
   messages_list.rst
   message_control.rst

doc/user_guide/messages/message_control.rst

@@ -3,11 +3,7 @@
 Messages control
 ================
 
-``pylint`` has an advanced message control for its checks, offering the ability
-to enable / disable a message either from the command line or from the configuration
-file, as well as from the code itself.
-
-For all of these controls, ``pylint`` accepts the following values:
+In order to control messages, ``pylint`` accepts the following values:
 
 * a symbolic message: ``no-member``, ``undefined-variable`` etc.