Wish: link anchors for docstring sections

[jnothman]

It would be great if each docstring section had its own link anchor (perhaps with corresponding sphinx role, or perhaps just a ref for simplicity), and even better if each entry in a parameter list had its own link anchor.

Given these link anchors, linking generated parameter names in function singatures to their respective descriptions would be wonderful.

[pv]

The sphinx `.. rubric::` that doesn't add them was used here iirc is because underline titles don't work inside auto-docstrings.