link to relative venv reference implementation

Author: rickeylev

peps/pep-0796.rst

@@ -170,7 +170,10 @@ Reference Implementation
 A reference implementation is available by using the combination of:
 
 * Python runtime from `rickeylev/feat.relative.pyvenv.home <https://github.com/python/cpython/compare/main...rickeylev:cpython:feat.relative.pyvenv.home>`__
-* rules_python with (todo: link to branch that uses above)
+* Relative venv from `rickeylev/relvenv <https://github.com/rickeylev/relvenv>`__
+
+And following the
+`relvenv README <https://github.com/rickeylev/relvenv/blob/main/README.md>`__.
 
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