Link in literals concept block is broken

@vaeng Great work on the literals concept in the C++ track. Unfortunately, the link inside the “Advanced” block is not resolved.

I put up a PR that should fix it.

I think this happens because special blocks are rendered standalone. So the link cannot be resolved if it is only mentioned at the bottom of the file.

Here is an example where it works: exercises/concept/guidos-gorgeous-lasagna/.docs/ from the Python track is rendered correctly (see the links in the Note block).