With @floam's recent work, we're now trying to use more semantic markup. That's cool.

Unfortunately, while :envvar: links to the definition of the corresponding envvar, I can't see :program: do the same.

I think the actual syntax to define a program section is:

.. program:: name

with the double colons and the space after them (at least emacs' sphinx mode doesn't highlight them if that's not added). Some of the definitions lack spaces or don't exist (e.g. echo doesn't have a program definition).

Whether with that, or without, I can't see e.g. the link from return in https://github.com/fish-shell/fish-shell/blob/master/doc_src/commands.rst#keywords working.

In addition, all of the links to fish_add_path are broken because they still use the label, which has now been removed.

If we can't figure out how to make it link, we should revert to using normal :ref: links again.

Note: This should block a 3.4 release