markup correction

Doc/api/newtypes.tex

@@ -1396,7 +1396,7 @@ might be collected by a garbage collection on any thread).  This is
 not a problem for Python API calls, since the thread on which
 tp_dealloc is called will own the Global Interpreter Lock (GIL).
 However, if the object being destroyed in turn destroys objects from
-some other C or C++ library, care should be taken to ensure that
+some other C or \Cpp{} library, care should be taken to ensure that
 destroying those objects on the thread which called tp_dealloc will
 not violate any assumptions of the library.