md code block params not compiled to rst correctly

[TheTripleV]

```Java
:lineno-start: 19
PWMSparkMax armMotorCtrl;

might need a newline there, unsure

[sciencewhiz]

I tried new lines both before and after the :lineno-start: and it didn't help

[sciencewhiz]

I'm pretty sure the issue is that redown adds two newlines after the code-block. When there's an option for the code block, like the lineno, the second newline shouldn't be added.

frc-docs/source/_extensions/redown.py

Line 70 in dcbf862

ret += btindent + f".. code-block:: {lang}\n\n"