Regex for language code block

[nitnelave]

Hello,

I often use language named code block, like so:

    ```C
    int a;
    ```

But your plugin doesn't support triple backtick.

A simple way to do that would be to add this line in code.vim:

    syntax region mkdCode    start=/\s*```[^`]*/   end=/[^`]*```\s*/

[alexvbush]

:+1: