Fix up bad git subtree import.

README.rst

@@ -17,6 +17,7 @@ Projects
 + ``par/``: `A Pamphlet Against R <https://panicz.github.io/pamphlet/>`_
 + ``pio/``: `PlatformIO <https://platformio.org/>`_ projects
 + ``practical_prolog/``: `The Practice of Prolog <https://mitpress.mit.edu/books/practice-prolog>`_
++ ``qc/``: Quantum computing experiments
 + ``uc/``: `Understanding Computation <http://computationbook.com/>`_
 
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