It ignores the following URLs:
 * Which are external to the website. This could be enabled in the
   future, but will have a big performance hit.
 * Ending in /news/, because that aggregates individual news posts which
   will get checked anyway.
 * Posts from 2015 or earlier (feel free to fix these at some point, but
   can't be bothered right now).
 * .*/packages/.* to avoid adding another 2000 pages to the list.
 * Only ends up checking the English site, because the rest will have
   the same links generated anyway.