Avoid reference to specific versions of Python where possible.

This partially addresses SourceForge bug #114318.

Doc/lib/libsite.tex

@@ -39,10 +39,10 @@ refers to a directory (rather than a file).  No item is added to
 
 For example, suppose \code{sys.prefix} and \code{sys.exec_prefix} are
 set to \file{/usr/local}.  The Python \version\ library is then
-installed in \file{/usr/local/lib/python1.5} (note that only the first 
-three characters of \code{sys.version} are used to form the path
-name).  Suppose this has a subdirectory
-\file{/usr/local/lib/python1.5/site-packages} with three
+installed in \file{/usr/local/lib/python\var{version}} (where
+\var{version} is the first three characters of \code{sys.version}).
+Suppose this has a subdirectory
+\file{/usr/local/lib/python\var{version}/site-packages} with three
 subsubdirectories, \file{foo}, \file{bar} and \file{spam}, and two
 path configuration files, \file{foo.pth} and \file{bar.pth}.  Assume
 \file{foo.pth} contains the following: