Add todo item for grouping broken links by link target

[ikiwiki] / doc / todo / brokenlinks_should_group_links_to_a_page.mdwn

I would find the [[plugins/brokenlinks]] listing much easier to use if it
grouped all the links to a single missing page on one line, rather than showing
one line per page that links to the missing page.

I think this would work well as the default; however, if people prefer the
current behavior, perhaps brokenlinks could have an option to group by link
target.

--[[JoshTriplett]]