Add some chapter introductions (not linked into the LibRef yet)
diff --git a/Doc/lib/filesys.tex b/Doc/lib/filesys.tex
new file mode 100644
index 0000000..0c682c8
--- /dev/null
+++ b/Doc/lib/filesys.tex
@@ -0,0 +1,18 @@
+\chapter{File and Directory Access}
+\label{filesys}
+
+The modules described in this chapter deal with disk files and
+directories. For example, there are modules for reading the
+properties of files, manipulating paths in a portable way, and
+creating temporary files. The full list of modules in this chapter is:
+
+\localmoduletable
+
+% XXX can this be included in the seealso environment? --amk
+Also see section \ref{bltin-file-objects} for a description
+of Python's built-in file objects.
+
+\begin{seealso}
+ \seemodule{os}{Operating system interfaces, including functions to
+ work with files at a lower level than the built-in file object.}
+\end{seealso}