There's a bit of uninterpreted RST markup:

3.6.. _tut-using:

at the top of the second section of the tutorial (https://docs.python.org/3.6/tutorial/interpreter.html) in the documentation for 3.6 only.  (I can see this in the offline copy I received with 3.6.0a1 as well.)

It appears that this originated in 96328:dfe62f685538, which changed various references to Python to say 3.6 instead of 3.5.  This line had formerly just said:

.. _tut-using:

My best guess is that this was just an accident.  I can't find a precedent or meaning for the changed notation, and there were no similar changes to any other files, either.  I've included a patch for this line.