Update pep-0423.rst

Author: johnzhou721

peps/pep-0423.rst

@@ -823,7 +823,7 @@ References and footnotes:
 .. _`in development official packaging documentation`:
    http://docs.python.org/dev/packaging/
 .. _`The Hitchhiker's Guide to Packaging`:
-   http://guide.python-distribute.org/specification.html#naming-specification
+   https://the-hitchhikers-guide-to-packaging.readthedocs.io/en/latest/
 
 
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