Minor typo of the word "declare"

docs/examples/userguide/wrapping_CPlusPlus/Rectangle.pxd

 cdef extern from "Rectangle.cpp":
     pass
 
-# Decalre the class with cdef
+# Declare the class with cdef
 cdef extern from "Rectangle.h" namespace "shapes":
     cdef cppclass Rectangle:
         Rectangle() except +