There's no real point in linking to a page offering users to choose a
heading when there's only one heading to choose.
So we're linking to the investments index instead.
Note we're absolutely positioning the link instead of the icon; that way
keyboard users will be able to focus on the icon. Until now, users would
focus on an empty link.
For the same reason, we couldn't use `click_link` with Capybara, since
it would fail to click an empty link. Now we can.
Co-authored-by: Javi Martín <javim@elretirao.net>
