Add bmo-wish query for xkcd

dotfiles/config/bmo/wish.ini

@@ -90,3 +90,4 @@
     w       = http://en.wikipedia.org/wiki/%s
     wa      = https://www.wolframalpha.com/input/?i=%s
     yt      = https://www.youtube.com/results?search_query=%s
+    xkcd    = https://xkcd.com/%s/