Adding basic imputil documentation.
diff --git a/Doc/library/modules.rst b/Doc/library/modules.rst
index 2590a3a..ec6f7cd 100644
--- a/Doc/library/modules.rst
+++ b/Doc/library/modules.rst
@@ -14,6 +14,7 @@
 .. toctree::
 
    imp.rst
+   imputil.rst
    zipimport.rst
    pkgutil.rst
    modulefinder.rst