Added some comments on the interaction of reload() and extension modules.

Based on comments from Chris Barker <cbarker@jps.net>.

Doc/ext/ext.tex

@@ -435,7 +435,7 @@ int main(int argc, char **argv)
     initspam();
 \end{verbatim}
 
-And example may be found in the file \file{Demo/embed/demo.c} in the
+An example may be found in the file \file{Demo/embed/demo.c} in the
 Python source distribution.
 
 \strong{Note:}  Removing entries from \code{sys.modules} or importing
@@ -444,6 +444,11 @@ following a \cfunction{fork()} without an intervening
 \cfunction{exec()}) can create problems for some extension modules.
 Extension module authors should exercise caution when initializing
 internal data structures.
+Note also that the \function{reload()} function can be used with
+extension modules, and will call the module initialization function
+(\cfunction{initspam()} in the example), but will not load the module
+again if it was loaded from a dynamically loadable object file
+(\file{.so} on \UNIX, \file{.dll} on Windows).
 
 A more substantial example module is included in the Python source
 distribution as \file{Modules/xxmodule.c}.  This file may be used as a