Code block syntax in markdown does not render in html

[gao-hongnan]

In the tutorial, we can typeset code in markdown as such:

1+2+3

however, I'd like the original RTD syntax with additional code blocks such as linenos, which helps to point out the line number.

.. code-block:: python
    :linenos:

    a = 2
    b = 3

Are there any hacks to make this appear?