Cross-reference Invalid Configuration with return code and mastering …

…conditional (conan-io#1263)

mastering/conditional.rst

@@ -68,6 +68,11 @@ There are two approaches for this situation:
           if self.settings.os == "Windows":
             raise ConanInvalidConfiguration("This library is not compatible with Windows")
 
+  .. tip::
+
+      Use the :ref:`invalid_configuration` exception to make Conan return with a special error code. This will indicate that the
+      configuration used for settings or options is not supported.
+
   This same method is also valid for ``options`` and ``config_options()`` method and it is commonly used to remove options for one setting:
 
   .. code-block:: python

reference/commands/return_codes.rst

@@ -45,6 +45,8 @@ Return code: ``5``
 
 Execution terminated due to ``SIGTERM`` signal.
 
+.. _invalid_configuration_return_code:
+
 Invalid configuration
 ---------------------
 

reference/conanfile/methods.rst

@@ -439,7 +439,7 @@ it is an example of a recipe for a library that doesn't support Windows operatin
         if self.settings.os != "Windows":
             raise ConanInvalidConfiguration("Library MyLib is only supported for Windows")
 
-This exception will be propagated and Conan application will exit with the error code ``6``.
+This exception will be propagated and Conan application will finish with a :ref:`special return code <invalid_configuration_return_code>`.
 
 requirements()
 --------------