Remove landing page link to PyPI migration guide (pypa#575)

Author: pradyunsg

source/index.rst

@@ -31,8 +31,6 @@ happily accept any :doc:`contributions and feedback <contribute>`. 😊
 .. _GitHub: https://github.com/pypa/python-packaging-user-guide
 .. _Python Packaging Authority: https://pypa.io
 
-.. note:: Looking for guidance on migrating from legacy PyPI to :term:`pypi.org`?
-   Please see :doc:`guides/migrating-to-pypi-org`.
 
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