changed file order in Sharing C Functions example

This order looks more logical, easier to read.

docs/src/userguide/sharing_declarations.rst

@@ -165,6 +165,11 @@ example,:
 
     cdef float cube(float)
 
+:file:`volume.pyx`::
+
+    cdef float cube(float x):
+        return x * x * x
+
 :file:`spammery.pyx`::
 
     from volume cimport cube
@@ -177,11 +182,6 @@ example,:
     menu("Main course", 3)
     menu("Dessert", 2)
 
-:file:`volume.pyx`::
-
-    cdef float cube(float x):
-        return x * x * x
-
 .. note::
 
     When a module exports a C function in this way, an object appears in the