Because we set a padding of 50px on anchorable elements to make
sure they are not obscured by the header, we need to raise the
z-index of links so they are not obscured by these paddings.
This renames the doc task to apidoc. The apidoc delegates to jsdoc3 currently. We will have additional documentation that is not built by jsdoc3. It makes sense to reserve the more general 'doc' name for building all documentation (not just apidoc).