add comment on NumPy compilation warnings (original patch by Giuseppe Attardi)

docs/src/reference/compilation.rst

@@ -88,6 +88,13 @@ the necessary include files, e.g. for NumPy::
 
     include_path = [numpy.get_include()]
 
+Note for Numpy users.  Despite this, you will still get warnings like the
+following from the compiler, because Cython is using a deprecated Numpy API::
+
+   .../include/numpy/npy_1_7_deprecated_api.h:15:2: warning: #warning "Using deprecated NumPy API, disable it by " "#defining NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION" [-Wcpp]
+
+For the time being, it is just a warning that you can ignore.
+
 If you need to specify compiler options, libraries to link with or other
 linker options you will need to create ``Extension`` instances manually
 (note that glob syntax can still be used to specify multiple extensions