fix typo

Doc/lib/distutils.tex

@@ -28,7 +28,7 @@ the \module{distutils} package, read
             for developers and packagers of Python modules.  This
             describes how to prepare \module{distutils}-based packages
             so that they may be easily installed into an existing
-            Python installaion.}
+            Python installation.}
 
   \seetitle[../inst/inst.html]{Installing Python Modules}{An
             ``administrators'' manual which includes information on