Fix warning.
diff --git a/Doc/documenting/markup.rst b/Doc/documenting/markup.rst
index 51fd47c..e6f6a52 100644
--- a/Doc/documenting/markup.rst
+++ b/Doc/documenting/markup.rst
@@ -785,7 +785,7 @@
 -------------
 
 The documentation system provides three substitutions that are defined by default.
-They are set in the build configuration file, see :ref:`doc-build-config`.
+They are set in the build configuration file :file:`conf.py`.
 
 .. describe:: |release|