fix typo in docs

--HG--
extra : rebase_source : 4cc5a2b5b9044e06fca82d216aa5a3c919abf033

docs/src/tutorial/cython_tutorial.rst

@@ -54,7 +54,7 @@ To use this to build your Cython file use the commandline options:
     $ python setup.py build_ext --inplace
 
 Which will leave a file in your local directory called :file:`helloworld.so` in unix
-or :file:`helloworld.dll` in Windows. Now to use this file: start the python
+or :file:`helloworld.pyd` in Windows. Now to use this file: start the python
 interpreter and simply import it as if it was a regular python module::
 
     >>> import helloworld