Update peps/pep-0788.rst

Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: ZeroIntensity

peps/pep-0788.rst

@@ -540,8 +540,9 @@ replace :c:func:`PyGILState_Ensure` and :c:func:`PyGILState_Release`.
 
     An opaque reference to a :term:`thread state`.
 
-    As of now, the interpreter will do nothing different for thread references,
-    but this may change in the future.
+    In the initial implementation, holding a thread reference will
+    not block finalization of threads or interpreters.
+    This may change in the future.
 
     This type is guaranteed to be pointer-sized.