Fix link to atom url.
Fix link to atom url.

The atom feed link on the navigation bar still points to `feeds/atom.xml`, which should be changed to `feeds/mazk.atom.xml`, as can be seen in this page: https://github.com/mazk/mazk/blob/dfe2e45948dd3280dc5b5478c11ab8dd730749f0/pelican-bootstrap3/templates/base.html#L223
Their is a FEED_URL option that controls all feed links. So we don't need to modify the templates.
mazk/mazk,mazk/mazk,mazk/mazk