Fix rst syntax in docs.

docs/src/quickstart/build.rst

@@ -35,7 +35,7 @@ The other methods are described in more detail in the :ref:`compilation` section
 
 
 Building a Cython module using setuptools
-----------------------------------------
+-----------------------------------------
 
 Imagine a simple "hello world" script in a file ``hello.pyx``:
 

docs/src/userguide/numpy_pythran.rst

@@ -17,7 +17,7 @@ This can lead to really interesting speedup in some cases, going from 2 up to
 Please note that this feature is experimental.
 
 Usage example with setuptools
-----------------------------
+-----------------------------
 
 You first need to install Pythran. See its `documentation
 <https://pythran.readthedocs.io/>`_ for more information.