fix title underlines

Author: rickeylev

peps/pep-0796.rst

@@ -107,7 +107,7 @@ i.e. it's equivalent to using that value verbatim in ``pyvenv.cfg``.
 
 
 CPython Runtime Changes
-======================
+=======================
 
 The CPython runtime itself *almost* already supports relative paths. The
 primitives are there, so the only change needed is to define how it resolves
@@ -180,7 +180,7 @@ nor how downstream tools (e.g. installers) should identify them or process
 them. These questions are best addressed separately by tool owners.
 
 References
-=========
+==========
 
 * `rules_python <https://github.com/bazel-contrib/rules_python>`__: implements
   host-relocatable virtual environments.